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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd"> <html><head><title>openMSP430 Serial Debug Interface</title></head><body> <a name="TOC"></a> <h3>Table of content</h3> <ul> <li><a href="#1.%20Introduction"> 1. Introduction</a></li> <li><a href="#2.%20Debug%20Unit"> 2. Debug Unit</a> <ul> <li><a href="#2.1%20Register%20Mapping"> 2.1 Register Mapping</a></li> <li><a href="#2.2%20CPU%20Control/Status%20Registers"> 2.2 CPU Control/Status Registers</a></li> <ul> <li><a href="#2.2.1%20CPU_ID"> 2.2.1 CPU_ID</a></li> <li><a href="#2.2.2%20CPU_CTL"> 2.2.2 CPU_CTL</a></li> <li><a href="#2.2.3%20CPU_STAT"> 2.2.3 CPU_STAT</a></li> </ul> <li><a href="#2.3%20Memory%20Access%20Registers"> 2.3 Memory Access Registers</a></li> <ul> <li><a href="#2.3.1%20MEM_CTL"> 2.3.1 MEM_CTL</a></li> <li><a href="#2.3.2%20MEM_ADDR"> 2.3.2 MEM_ADDR</a></li> <li><a href="#2.3.3%20MEM_DATA"> 2.3.3 MEM_DATA</a></li> <li><a href="#2.3.4%20MEM_CNT"> 2.3.4 MEM_CNT</a></li> </ul> <li><a href="#2.4%20Hardware%20Breakpoint%20Unit%20Registers">2.4 Hardware Breakpoint Unit Registers</a></li> <ul> <li><a href="#2.4.1%20BRKx_CTL"> 2.4.1 BRKx_CTL</a></li> <li><a href="#2.4.2%20BRKx_STAT"> 2.4.2 BRKx_STAT</a></li> <li><a href="#2.4.3%20BRKx_ADDR0"> 2.4.3 BRKx_ADDR0</a></li> <li><a href="#2.4.4%20BRKx_ADDR1"> 2.4.4 BRKx_ADDR1</a></li> </ul> </ul> </li> <li><a href="#3.%20Debug%20Communication%20Interface:%20UART"> 3. Debug Communication Interface: UART</a> <ul> <li><a href="#3.1%20Serial%20communication%20protocol:%208N1"> 3.1 Serial communication protocol: 8N1</a></li> <li><a href="#3.2%20Synchronization%20frame"> 3.2 Synchronization frame</a></li> <li><a href="#3.3%20Read/Write%20access%20to%20the%20debug%20registers"> 3.3 Read/Write access to the debug registers</a></li> <ul> <li><a href="#3.3.1%20Command%20Frame"> 3.3.1 Command Frame</a></li> <li><a href="#3.3.2%20Write%20access"> 3.3.2 Write access</a></li> <li><a href="#3.3.3%20Read%20access"> 3.3.3 Read access</a></li> </ul> <li><a href="#3.4%20Read/Write%20burst%20implementation%20for%20the%20CPU%20Memory%20access">3.4 Read/Write burst implementation for the CPU Memory access</a></li> <ul> <li><a href="#3.4.1%20Write%20Burst%20access"> 3.4.1 Write Burst access</a></li> <li><a href="#3.4.2%20Read%20Burst%20access"> 3.4.2 Read Burst access</a></li> </ul> </ul> </li></ul> <a name="1. Introduction"></a> <h1>1. Introduction</h1> The original MSP430 from TI provides a serial debug interface to allow in-system software debugging. In that case, the communication with the host computer is typically built on a JTAG or Spy-Bi-Wire serial protocol. However, the global debug architecture from the MSP430 is unfortunately poorly documented on the web (and is also probably tightly linked with the internal core architecture). <br><br>A custom module has therefore been implemented for the openMSP430. The communication with the host is done with a simple two-wire RS232 cable (8N1 serial protocol) and the debug unit provides all the required features for Nexus Class 3 debugging (beside trace), namely: <ul> <li>CPU control (run, stop, step, reset).</li> <li>Software & hardware breakpoint support.</li> <li>Hardware watchpoint support.<br> </li> <li>Memory read/write on-the-fly (no need to halt execution).</li> <li>CPU registers read/write on-the-fly (no need to halt execution).</li> </ul> <a name="2. Debug Unit"></a> <div style="text-align: right;"><a href="#TOC">Top</a></div> <h1>2. Debug Unit</h1> <a name="2.1 Register Mapping"></a> <h2>2.1 Register Mapping</h2> The following table summarize the complete debug register set accessible through the debug communication interface: <br><br> <table border="1"> <tbody><tr align="center"> <td rowspan="2"><b><small>Register Name</small></b></td> <td rowspan="2"><b><small>Address</small></b></td> <td colspan="16"><b><small>Bit Field</small></b></td> </tr> <tr align="center"> <td><small>15</small></td><td><small>14</small></td> <td><small>13</small></td><td><small>12</small></td> <td><small>11</small></td><td><small>10</small></td> <td><small> 9</small></td><td><small> 8</small></td> <td><small> 7</small></td><td><small> 6</small></td> <td><small> 5</small></td><td><small> 4</small></td> <td><small> 3</small></td><td><small> 2</small></td> <td><small> 1</small></td><td><small> 0</small></td> </tr> <tr align="center"> <td><small><a href="#2.2.1%20CPU_ID">CPU_ID_LO</a></small></td> <td><small>0x00</small></td> <td colspan="7"><font size="-5">PER_SPACE</font></td> <td colspan="5"><font size="-5">USER_VERSION</font></td> <td colspan="1"><font size="-5">ASIC</font></td> <td colspan="3"><font size="-5">CPU_VERSION</font></td> </tr> <tr align="center"> <td><small><a href="#2.2.1%20CPU_ID">CPU_ID_HI</a></small></td> <td><small>0x01</small></td> <td colspan="6"><font size="-5">PMEM_SIZE</font></td> <td colspan="9"><font size="-5">DMEM_SIZE</font></td> <td colspan="1"><font size="-5">MPY</font></td> </tr> <tr align="center"> <td><small><a href="#2.2.2%20CPU_CTL">CPU_CTL</a></small></td> <td><small>0x02</small></td> <td colspan="9"><font size="-5">Reserved</font></td> <td><font size="-5">CPU_RST</font></td> <td><font size="-5">RST_BRK_EN</font></td> <td><font size="-5">FRZ_BRK_EN</font></td> <td><font size="-5">SW_BRK_EN</font></td> <td><font size="-5">ISTEP</font></td> <td><font size="-5">RUN</font></td> <td><font size="-5">HALT</font></td> </tr> <tr align="center"> <td><small><a href="#2.2.3%20CPU_STAT">CPU_STAT</a></small></td> <td><small>0x03</small></td> <td colspan="8"><font size="-5">Reserved</font></td> <td><font size="-5">HWBRK3_PND</font></td> <td><font size="-5">HWBRK2_PND</font></td> <td><font size="-5">HWBRK1_PND</font></td> <td><font size="-5">HWBRK0_PND</font></td> <td><font size="-5">SWBRK_PND</font></td> <td><font size="-5">PUC_PND</font></td> <td><font size="-5">Res.</font></td> <td><font size="-5">HALT_RUN</font></td> </tr> <tr align="center"> <td><small><a href="#2.3.1%20MEM_CTL">MEM_CTL</a></small></td> <td><small>0x04</small></td> <td colspan="12"><font size="-5">Reserved</font></td> <td><font size="-5">B/W</font></td> <td><font size="-5">MEM/REG</font></td> <td><font size="-5">RD/WR</font></td> <td><font size="-5">START</font></td> </tr> <tr align="center"> <td><small><a href="#2.3.2%20MEM_ADDR">MEM_ADDR</a></small></td> <td><small>0x05</small></td> <td colspan="16"><font size="-5">MEM_ADDR[15:0]</font></td> </tr> <tr align="center"> <td><small><a href="#2.3.3%20MEM_DATA">MEM_DATA</a></small></td> <td><small>0x06</small></td> <td colspan="16"><font size="-5">MEM_DATA[15:0]</font></td> </tr> <tr align="center"> <td><small><a href="#2.3.4%20MEM_CNT">MEM_CNT</a></small></td> <td><small>0x07</small></td> <td colspan="16"><font size="-5">MEM_CNT[15:0]</font></td> </tr> <tr align="center"> <td><small><a href="#2.4.1%20BRKx_CTL">BRK0_CTL</a></small></td> <td><small>0x08</small></td> <td colspan="11"><font size="-5">Reserved</font></td> <td><font size="-5">RANGE_MODE</font></td> <td><font size="-5">INST_EN</font></td> <td><font size="-5">BREAK_EN</font></td> <td colspan="2"><font size="-5">ACCESS_MODE</font></td> </tr> <tr align="center"> <td><small><a href="#2.4.2%20BRKx_STAT">BRK0_STAT</a></small></td> <td><small>0x09</small></td> <td colspan="10"><font size="-5">Reserved</font></td> <td><font size="-5">RANGE_WR</font></td> <td><font size="-5">RANGE_RD</font></td> <td><font size="-5">ADDR1_WR</font></td> <td><font size="-5">ADDR1_RD</font></td> <td><font size="-5">ADDR0_WR</font></td> <td><font size="-5">ADDR0_RD</font></td> </tr> <tr align="center"> <td><small><a href="#2.4.3%20BRKx_ADDR0">BRK0_ADDR0</a></small></td> <td><small>0x0A</small></td> <td colspan="16"><font size="-5">BRK_ADDR0[15:0]</font></td> </tr> <tr align="center"> <td><small><a href="#2.4.4%20BRKx_ADDR1">BRK0_ADDR1</a></small></td> <td><small>0x0B</small></td> <td colspan="16"><font size="-5">BRK_ADDR1[15:0]</font></td> </tr> <tr align="center"> <td><small><a href="#2.4.1%20BRKx_CTL">BRK1_CTL</a></small></td> <td><small>0x0C</small></td> <td colspan="11"><font size="-5">Reserved</font></td> <td><font size="-5">RANGE_MODE</font></td> <td><font size="-5">INST_EN</font></td> <td><font size="-5">BREAK_EN</font></td> <td colspan="2"><font size="-5">ACCESS_MODE</font></td> </tr> <tr align="center"> <td><small><a href="#2.4.2%20BRKx_STAT">BRK1_STAT</a></small></td> <td><small>0x0D</small></td> <td colspan="10"><font size="-5">Reserved</font></td> <td><font size="-5">RANGE_WR</font></td> <td><font size="-5">RANGE_RD</font></td> <td><font size="-5">ADDR1_WR</font></td> <td><font size="-5">ADDR1_RD</font></td> <td><font size="-5">ADDR0_WR</font></td> <td><font size="-5">ADDR0_RD</font></td> </tr> <tr align="center"> <td><small><a href="#2.4.3%20BRKx_ADDR0">BRK1_ADDR0</a></small></td> <td><small>0x0E</small></td> <td colspan="16"><font size="-5">BRK_ADDR0[15:0]</font></td> </tr> <tr align="center"> <td><small><a href="#2.4.4%20BRKx_ADDR1">BRK1_ADDR1</a></small></td> <td><small>0x0F</small></td> <td colspan="16"><font size="-5">BRK_ADDR1[15:0]</font></td> </tr> <tr align="center"> <td><small><a href="#2.4.1%20BRKx_CTL">BRK2_CTL</a></small></td> <td><small>0x10</small></td> <td colspan="11"><font size="-5">Reserved</font></td> <td><font size="-5">RANGE_MODE</font></td> <td><font size="-5">INST_EN</font></td> <td><font size="-5">BREAK_EN</font></td> <td colspan="2"><font size="-5">ACCESS_MODE</font></td> </tr> <tr align="center"> <td><small><a href="#2.4.2%20BRKx_STAT">BRK2_STAT</a></small></td> <td><small>0x11</small></td> <td colspan="10"><font size="-5">Reserved</font></td> <td><font size="-5">RANGE_WR</font></td> <td><font size="-5">RANGE_RD</font></td> <td><font size="-5">ADDR1_WR</font></td> <td><font size="-5">ADDR1_RD</font></td> <td><font size="-5">ADDR0_WR</font></td> <td><font size="-5">ADDR0_RD</font></td> </tr> <tr align="center"> <td><small><a href="#2.4.3%20BRKx_ADDR0">BRK2_ADDR0</a></small></td> <td><small>0x12</small></td> <td colspan="16"><font size="-5">BRK_ADDR0[15:0]</font></td> </tr> <tr align="center"> <td><small><a href="#2.4.4%20BRKx_ADDR1">BRK2_ADDR1</a></small></td> <td><small>0x13</small></td> <td colspan="16"><font size="-5">BRK_ADDR1[15:0]</font></td> </tr> <tr align="center"> <td><small><a href="#2.4.1%20BRKx_CTL">BRK3_CTL</a></small></td> <td><small>0x14</small></td> <td colspan="11"><font size="-5">Reserved</font></td> <td><font size="-5">RANGE_MODE</font></td> <td><font size="-5">INST_EN</font></td> <td><font size="-5">BREAK_EN</font></td> <td colspan="2"><font size="-5">ACCESS_MODE</font></td> </tr> <tr align="center"> <td><small><a href="#2.4.2%20BRKx_STAT">BRK3_STAT</a></small></td> <td><small>0x15</small></td> <td colspan="10"><font size="-5">Reserved</font></td> <td><font size="-5">RANGE_WR</font></td> <td><font size="-5">RANGE_RD</font></td> <td><font size="-5">ADDR1_WR</font></td> <td><font size="-5">ADDR1_RD</font></td> <td><font size="-5">ADDR0_WR</font></td> <td><font size="-5">ADDR0_RD</font></td> </tr> <tr align="center"> <td><small><a href="#2.4.3%20BRKx_ADDR0">BRK3_ADDR0</a></small></td> <td><small>0x16</small></td> <td colspan="16"><font size="-5">BRK_ADDR0[15:0]</font></td> </tr> <tr align="center"> <td><small><a href="#2.4.4%20BRKx_ADDR1">BRK3_ADDR1</a></small></td> <td><small>0x17</small></td> <td colspan="16"><font size="-5">BRK_ADDR1[15:0]</font></td> </tr> </tbody></table> <a name="2.2 CPU Control/Status Registers"></a> <div style="text-align: right;"><a href="#TOC">Top</a></div> <h2>2.2 CPU Control/Status Registers</h2> <a name="2.2.1 CPU_ID"></a> <h3>2.2.1 CPU_ID</h3> This 32 bit read-only register holds the program and data memory size information of the implemented openMSP430. <br><br> <table border="1"> <tbody><tr align="center"> <td rowspan="2"><b><small>Register Name</small></b></td> <td rowspan="2"><b><small>Address</small></b></td> <td colspan="16"><b><small>Bit Field</small></b></td> </tr> <tr align="center"> <td><small>15</small></td><td><small>14</small></td> <td><small>13</small></td><td><small>12</small></td> <td><small>11</small></td><td><small>10</small></td> <td><small> 9</small></td><td><small> 8</small></td> <td><small> 7</small></td><td><small> 6</small></td> <td><small> 5</small></td><td><small> 4</small></td> <td><small> 3</small></td><td><small> 2</small></td> <td><small> 1</small></td><td><small> 0</small></td> </tr> <tr align="center"> <td><small>CPU_ID_LO</small></td> <td><small>0x00</small></td> <td colspan="7"><font size="-5">PER_SPACE</font></td> <td colspan="5"><font size="-5">USER_VERSION</font></td> <td colspan="1"><font size="-5">ASIC</font></td> <td colspan="3"><font size="-5">CPU_VERSION</font></td> </tr> <tr align="center"> <td><small>CPU_ID_HI</small></td> <td><small>0x01</small></td> <td colspan="6"><font size="-5">PMEM_SIZE</font></td> <td colspan="9"><font size="-5">DMEM_SIZE</font></td> <td colspan="1"><font size="-5">MPY</font></td> </tr> </tbody></table> <br> <table border="0"> <tbody><tr> <td> </td><td valign="top"><li><b>CPU_VERSION</b></li></td> <td>: Current CPU version<br> </td> </tr> <tr> <td> </td><td valign="top"><li><b>ASIC</b></li></td> <td>: Defines if the ASIC specific features are enabled in the current openMSP430 implementation.</td> </tr> <tr> <td> </td><td valign="top"><li><b>USER_VERSION</b></li></td> <td>: Reflects the value defined in the <b>openMSP430_defines.v</b> file.</td> </tr> <tr> <td> </td><td valign="top"><li><b>PER_SPACE</b></li></td> <td>: Peripheral address space for the current implementation (byte size = PER_SPACE*512)</td> </tr> <tr> <td> </td><td valign="top"><li><b>MPY</b></li></td> <td>: This bit is set if the hardware multiplier is included in the current implementation</td> </tr> <tr> <td> </td><td valign="top"><li><b>DMEM_SIZE</b></li></td> <td>: Data memory size for the current implementation (byte size = DMEM_SIZE*128)</td> </tr> <tr> <td> </td><td valign="top"><li><b>PMEM_SIZE</b></li></td> <td>: Progam memory size for the current implementation (byte size = PMEM_SIZE*1024)</td> </tr> </tbody></table> <a name="2.2.2 CPU_CTL"></a> <h3>2.2.2 CPU_CTL</h3> This 8 bit read-write register is used to control the CPU and to configure some basic debug features. After a POR, this register is set to 0x10 or 0x30 (depending on the <span style="font-weight: bold;">DBG_RST_BRK_EN</span> configuration option). <br><br> <table border="1"> <tbody><tr align="center"> <td rowspan="2"><b><small>Register Name</small></b></td> <td rowspan="2"><b><small>Address</small></b></td> <td colspan="16"><b><small>Bit Field</small></b></td> </tr> <tr align="center"> <td><small> 7</small></td><td><small> 6</small></td> <td><small> 5</small></td><td><small> 4</small></td> <td><small> 3</small></td><td><small> 2</small></td> <td><small> 1</small></td><td><small> 0</small></td> </tr> <tr align="center"> <td><small>CPU_CTL</small></td> <td><small>0x02</small></td> <td><font size="-5">Res.</font></td> <td><font size="-5">CPU_RST</font></td> <td><font size="-5">RST_BRK_EN</font></td> <td><font size="-5">FRZ_BRK_EN</font></td> <td><font size="-5">SW_BRK_EN</font></td> <td><font size="-5">ISTEP</font></td> <td><font size="-5">RUN</font></td> <td><font size="-5">HALT</font></td> </tr> </tbody></table> <br> <table border="0"> <tbody><tr> <td> </td><td valign="top"><li><b>CPU_RST</b></li></td> <td>: Setting this bit to 1 will activate the PUC reset. Setting it back to 0 will release it.</td> </tr> <tr> <td> </td><td valign="top"><li><b>RST_BRK_EN</b></li></td> <td>: If set to 1, the CPU will automatically break after a PUC occurrence.</td> </tr> <tr> <td> </td><td valign="top"><li><b>FRZ_BRK_EN</b></li></td> <td>: If set to 1, the timers and watchdog are frozen when the CPU is halted.</td> </tr> <tr> <td> </td><td valign="top"><li><b>SW_BRK_EN</b></li></td> <td>: Enables the software breakpoint detection.</td> </tr> <tr> <td> </td><td valign="top"><li><b>ISTEP</b><sup>1</sup></li></td> <td>: Writing 1 to this bit will perform a single instruction step if the CPU is halted.</td> </tr> <tr> <td> </td><td valign="top"><li><b>RUN</b><sup>1</sup></li></td> <td>: Writing 1 to this bit will get the CPU out of halt state.</td> </tr> <tr> <td> </td><td valign="top"><li><b>HALT</b><sup>1</sup></li></td> <td>: Writing 1 to this bit will put the CPU in halt state.</td> </tr> </tbody></table> <br><sup>1</sup>:this field is write-only and always reads back 0. <br> <a name="2.2.3 CPU_STAT"></a> <h3>2.2.3 CPU_STAT</h3> This 8 bit read-write register gives the global status of the debug interface. After a POR, this register is set to 0x00. <br><br> <table border="1"> <tbody><tr align="center"> <td rowspan="2"><b><small>Register Name</small></b></td> <td rowspan="2"><b><small>Address</small></b></td> <td colspan="16"><b><small>Bit Field</small></b></td> </tr> <tr align="center"> <td><small> 7</small></td><td><small> 6</small></td> <td><small> 5</small></td><td><small> 4</small></td> <td><small> 3</small></td><td><small> 2</small></td> <td><small> 1</small></td><td><small> 0</small></td> </tr> <tr align="center"> <td><small>CPU_STAT</small></td> <td><small>0x03</small></td> <td><font size="-5">HWBRK3_PND</font></td> <td><font size="-5">HWBRK2_PND</font></td> <td><font size="-5">HWBRK1_PND</font></td> <td><font size="-5">HWBRK0_PND</font></td> <td><font size="-5">SWBRK_PND</font></td> <td><font size="-5">PUC_PND</font></td> <td><font size="-5">Res.</font></td> <td><font size="-5">HALT_RUN</font></td> </tr> </tbody></table> <br> <table border="0"> <tbody><tr> <td> </td><td valign="top"><li><b>HWBRK3_PND</b></li></td> <td>: This bit reflects if one of the Hardware Breakpoint Unit 3 status bit is set (i.e. BRK3_STAT≠0).</td> </tr> <tr> <td> </td><td valign="top"><li><b>HWBRK2_PND</b></li></td> <td>: This bit reflects if one of the Hardware Breakpoint Unit 2 status bit is set (i.e. BRK2_STAT≠0).</td> </tr> <tr> <td> </td><td valign="top"><li><b>HWBRK1_PND</b></li></td> <td>: This bit reflects if one of the Hardware Breakpoint Unit 1 status bit is set (i.e. BRK1_STAT≠0).</td> </tr> <tr> <td> </td><td valign="top"><li><b>HWBRK0_PND</b></li></td> <td>: This bit reflects if one of the Hardware Breakpoint Unit 0 status bit is set (i.e. BRK0_STAT≠0).</td> </tr> <tr> <td> </td><td valign="top"><li><b>SWBRK_PND</b></li></td> <td>: This bit is set to 1 when a software breakpoint occurred. It can be cleared by writing 1 to it.</td> </tr> <tr> <td> </td><td valign="top"><li><b>PUC_PND</b></li></td> <td>: This bit is set to 1 when a PUC reset occured. It can be cleared by writing 1 to it.</td> </tr> <tr> <td> </td><td valign="top"><li><b>HALT_RUN</b></li></td> <td>: This read-only bit gives the current status of the CPU: </td> </tr> <tr> <td> </td><td> </td> <td> 0 - CPU is running. <br> 1 - CPU is stopped. </td> </tr> </tbody></table> <a name="2.3 Memory Access Registers"></a> <div style="text-align: right;"><a href="#TOC">Top</a></div> <h2>2.3 Memory Access Registers</h2> The following four registers enable single and burst read/write access to both CPU-Registers and full memory address range. <br>In order to perform an access, the following sequences are typically done: <ul> <li>single read access (MEM_CNT=0):</li> <ol> <li>set MEM_ADDR with the memory address (or register number) to be read</li> <li>set MEM_CTL (in particular RD/WR=0 and START=1)</li> <li>read MEM_DATA</li> </ol> <li>single write access (MEM_CNT=0):</li> <ol> <li>set MEM_ADDR with the memory address (or register number) to be written</li> <li>set MEM_DATA with the data to be written</li> <li>set MEM_CTL (in particular RD/WR=1 and START=1)</li> </ol> <li>burst read/write access (MEM_CNT≠0):</li> <ul> <li>burst access are optimized for the communication interface used (i.e. for the UART). The burst sequence are therefore described in the corresponding section (<a href="#3.4%20Read/Write%20burst%20implementation%20for%20the%20CPU%20Memory%20access">3.4 Read/Write burst implementation for the CPU Memory access</a>)</li> </ul> </ul> <a name="2.3.1 MEM_CTL"></a> <h3>2.3.1 MEM_CTL</h3>This 8 bit read-write register is used to control the Memory and CPU-Register read/write access. After a POR, this register is set to 0x00. <br><br> <table border="1"> <tbody><tr align="center"> <td rowspan="2"><b><small>Register Name</small></b></td> <td rowspan="2"><b><small>Address</small></b></td> <td colspan="16"><b><small>Bit Field</small></b></td> </tr> <tr align="center"> <td><small> 7</small></td><td><small> 6</small></td> <td><small> 5</small></td><td><small> 4</small></td> <td><small> 3</small></td><td><small> 2</small></td> <td><small> 1</small></td><td><small> 0</small></td> </tr> <tr align="center"> <td><small>MEM_CTL</small></td> <td><small>0x04</small></td> <td colspan="4"><font size="-5">Reserved</font></td> <td><font size="-5">B/W</font></td> <td><font size="-5">MEM/REG</font></td> <td><font size="-5">RD/WR</font></td> <td><font size="-5">START</font></td> </tr> </tbody></table> <br> <table border="0"> <tbody><tr> <td> </td><td valign="top"><li><b>B/W</b></li></td> <td>: 0 - 16 bit access.</td> </tr> <tr> <td> </td><td> </td> <td> 1 - 8 bit access (not valid for CPU-Registers).</td> </tr> <tr> <td> </td><td valign="top"><li><b>MEM/REG</b></li></td> <td>: 0 - Memory access.</td> </tr> <tr> <td> </td><td> </td> <td> 1 - CPU-Register access.</td> </tr> <tr> <td> </td><td valign="top"><li><b>RD/WR</b></li></td> <td>: 0 - Read access.</td> </tr> <tr> <td> </td><td> </td> <td> 1 - Write access.</td> </tr> <tr> <td> </td><td valign="top"><li><b>START</b></li></td> <td>: 0- Do nothing</td> </tr> <tr> <td> </td><td> </td> <td> 1 - Initiate memory transfer.</td> </tr> </tbody></table> <a name="2.3.2 MEM_ADDR"></a> <h3>2.3.2 MEM_ADDR</h3>This 16 bit read-write register specifies the Memory or CPU-Register address to be used for the next read/write transfer. After a POR, this register is set to 0x0000. <br> <strong>Note:</strong> in case of burst (i.e. MEM_CNT≠0), this register specifies the first address of the burst transfer and will be incremented automatically as the burst goes (by 1 for 8-bit access and by 2 for 16-bit access). <br><br> <table border="1"> <tbody><tr align="center"> <td rowspan="2"><b><small>Register Name</small></b></td> <td rowspan="2"><b><small>Address</small></b></td> <td colspan="16"><b><small>Bit Field</small></b></td> </tr> <tr align="center"> <td><small>15</small></td><td><small>14</small></td> <td><small>13</small></td><td><small>12</small></td> <td><small>11</small></td><td><small>10</small></td> <td><small> 9</small></td><td><small> 8</small></td> <td><small> 7</small></td><td><small> 6</small></td> <td><small> 5</small></td><td><small> 4</small></td> <td><small> 3</small></td><td><small> 2</small></td> <td><small> 1</small></td><td><small> 0</small></td> </tr> <tr align="center"> <td><small>MEM_ADDR</small></td> <td><small>0x05</small></td> <td colspan="16"><font size="-5">MEM_ADDR[15:0]</font></td> </tr> </tbody></table> <br> <table border="0"> <tbody><tr> <td> </td><td valign="top"><li><b>MEM_ADDR</b></li></td> <td>: Memory or CPU-Register address to be used for the next read/write transfer.</td> </tr> </tbody></table> <a name="2.3.3 MEM_DATA"></a> <h3>2.3.3 MEM_DATA</h3>This 16 bit read-write register gives (wr) or receive (rd) the Memory or CPU-Register data for the next transfer. After a POR, this register is set to 0x0000. <br><br> <table border="1"> <tbody><tr align="center"> <td rowspan="2"><b><small>Register Name</small></b></td> <td rowspan="2"><b><small>Address</small></b></td> <td colspan="16"><b><small>Bit Field</small></b></td> </tr> <tr align="center"> <td><small>15</small></td><td><small>14</small></td> <td><small>13</small></td><td><small>12</small></td> <td><small>11</small></td><td><small>10</small></td> <td><small> 9</small></td><td><small> 8</small></td> <td><small> 7</small></td><td><small> 6</small></td> <td><small> 5</small></td><td><small> 4</small></td> <td><small> 3</small></td><td><small> 2</small></td> <td><small> 1</small></td><td><small> 0</small></td> </tr> <tr align="center"> <td><small>MEM_DATA</small></td> <td><small>0x06</small></td> <td colspan="16"><font size="-5">MEM_DATA[15:0]</font></td> </tr> </tbody></table> <br> <table border="0"> <tbody><tr> <td> </td><td valign="top"><li><b>MEM_DATA</b></li></td> <td>: if MEM_CTL.WR - data to be written during the next write transfer.</td> </tr> <tr> <td> </td><td> </td> <td> if MEM_CTL.RD - updated with the data from the read transfer</td> </tr> </tbody></table> <a name="2.3.4 MEM_CNT"></a> <h3>2.3.4 MEM_CNT</h3>This 16 bit read-write register controls the burst access to the Memory or CPU-Registers. If set to 0, a single access will occur, otherwise, a burst will be performed. The burst being optimized for the communication interface, more details are given <a href="#3.4%20Read/Write%20burst%20implementation%20for%20the%20CPU%20Memory%20access">there</a>. After a POR, this register is set to 0x0000. <br><br> <table border="1"> <tbody><tr align="center"> <td rowspan="2"><b><small>Register Name</small></b></td> <td rowspan="2"><b><small>Address</small></b></td> <td colspan="16"><b><small>Bit Field</small></b></td> </tr> <tr align="center"> <td><small>15</small></td><td><small>14</small></td> <td><small>13</small></td><td><small>12</small></td> <td><small>11</small></td><td><small>10</small></td> <td><small> 9</small></td><td><small> 8</small></td> <td><small> 7</small></td><td><small> 6</small></td> <td><small> 5</small></td><td><small> 4</small></td> <td><small> 3</small></td><td><small> 2</small></td> <td><small> 1</small></td><td><small> 0</small></td> </tr> <tr align="center"> <td><small>MEM_CNT</small></td> <td><small>0x07</small></td> <td colspan="16"><font size="-5">MEM_CNT[15:0]</font></td> </tr> </tbody></table> <br> <table border="0"> <tbody><tr> <td> </td><td valign="top"><li><b>MEM_CNT</b></li></td> <td>: =0 - a single access will be performed with the next transfer.</td> </tr> <tr> <td> </td><td> </td> <td> ≠0 - specifies the burst size for the next transfer (i.e number of data access). This field will be automatically decremented as the burst goes.</td> </tr> </tbody></table> <a name="2.4 Hardware Breakpoint Unit Registers"></a> <div style="text-align: right;"><a href="#TOC">Top</a></div> <h2>2.4 Hardware Breakpoint Unit Registers</h2> Depending on the <a href="http://opencores.org/project,openmsp430,core#2.1.3%20Configuration">defines</a> located in the "openmsp430_defines.v" file, up to four hardware breakpoint units can be included in the design. These units can be individually controlled with the following registers. <a name="2.4.1 BRKx_CTL"></a> <h3>2.4.1 BRKx_CTL</h3> This 8 bit read-write register controls the hardware breakpoint unit x. After a POR, this register is set to 0x00. <br><br> <table border="1"> <tbody><tr align="center"> <td rowspan="2"><b><small>Register Name</small></b></td> <td rowspan="2"><b><small>Address</small></b></td> <td colspan="16"><b><small>Bit Field</small></b></td> </tr> <tr align="center"> <td><small> 7</small></td><td><small> 6</small></td> <td><small> 5</small></td><td><small> 4</small></td> <td><small> 3</small></td><td><small> 2</small></td> <td><small> 1</small></td><td><small> 0</small></td> </tr> <tr align="center"> <td><small>BRKx_CTL</small></td> <td><small>0x08, 0x0C, 0x10, 0x14</small></td> <td colspan="3"><font size="-5">Reserved</font></td> <td><font size="-5">RANGE_MODE</font></td> <td><font size="-5">INST_EN</font></td> <td><font size="-5">BREAK_EN</font></td> <td colspan="2"><font size="-5">ACCESS_MODE</font></td> </tr> </tbody></table> <br> <table border="0"> <tbody><tr> <td> </td><td valign="top"><li><b>RANGE_MODE</b></li></td> <td>: 0 - Address match on BRK_ADDR0 or BRK_ADDR1 (normal mode)</td> </tr> <tr> <td> </td><td> </td> <td> 1 - Address match on BRK_ADDR0→BRK_ADDR1 range (range mode) <br><font color="red"><b>Note</b>: range mode is not supported by the core unless the `DBG_HWBRK_RANGE define is set to 1'b1 in the <i>openMSP430_define.v</i> file.</font></td> </tr> <tr> <td> </td><td valign="top"><li><b>INST_EN</b></li></td> <td>: 0 - Checks are done on the execution unit (data flow).</td> </tr> <tr> <td> </td><td> </td> <td> 1 - Checks are done on the frontend (instruction flow).</td> </tr> <tr> <td> </td><td valign="top"><li><b>BREAK_EN</b></li></td> <td>: 0 - Watchpoint mode enable (don't stop on address match).</td> </tr> <tr> <td> </td><td> </td> <td> 1 - Breakpoint mode enable (stop on address match).</td> </tr> <tr> <td> </td><td valign="top"><li><b>ACCESS_MODE</b></li></td> <td>: 00 - Disabled</td> </tr> <tr> <td> </td><td> </td> <td> 01 - Detect read access. <br> 10 - Detect write access. <br> 11 - Detect read/write access <br><b>Note</b>: '10' & '11' modes are not supported on the instruction flow</td> </tr> </tbody></table> <a name="2.4.2 BRKx_STAT"></a> <h3>2.4.2 BRKx_STAT</h3>This 8 bit read-write register gives the status of the hardware breakpoint unit x. Each status bit can be cleared by writing 1 to it. After a POR, this register is set to 0x00. <br><br> <table border="1"> <tbody><tr align="center"> <td rowspan="2"><b><small>Register Name</small></b></td> <td rowspan="2"><b><small>Address</small></b></td> <td colspan="16"><b><small>Bit Field</small></b></td> </tr> <tr align="center"> <td><small> 7</small></td><td><small> 6</small></td> <td><small> 5</small></td><td><small> 4</small></td> <td><small> 3</small></td><td><small> 2</small></td> <td><small> 1</small></td><td><small> 0</small></td> </tr> <tr align="center"> <td><small>BRKx_STAT</small></td> <td><small>0x09, 0x0D, 0x11, 0x15</small></td> <td colspan="2"><font size="-5">Reserved</font></td> <td><font size="-5">RANGE_WR</font></td> <td><font size="-5">RANGE_RD</font></td> <td><font size="-5">ADDR1_WR</font></td> <td><font size="-5">ADDR1_RD</font></td> <td><font size="-5">ADDR0_WR</font></td> <td><font size="-5">ADDR0_RD</font></td> </tr> </tbody></table> <br> <table border="0"> <tbody><tr> <td> </td><td valign="top"><li><b>RANGE_WR</b></li></td> <td>: This bit is set whenever the CPU performs a write access within the BRKx_ADDR0→BRKx_ADDR1 range (valid if RANGE_MODE=1 and ACCESS_MODE[1]=1).</td> </tr> <tr> <td> </td><td valign="top"><li><b>RANGE_RD</b></li></td> <td>: This bit is set whenever the CPU performs a read access within the BRKx_ADDR0→BRKx_ADDR1 range (valid if RANGE_MODE=1 and ACCESS_MODE[0]=1). <br><font color="red"><b>Note</b>: range mode is not supported by the core unless the `DBG_HWBRK_RANGE define is set to 1'b1 in the <i>openMSP430_define.v</i> file.</font></td> </tr> <tr> <td> </td><td valign="top"><li><b>ADDR1_WR</b></li></td> <td>: This bit is set whenever the CPU performs a write access at the BRKx_ADDR1 address (valid if RANGE_MODE=0 and ACCESS_MODE[1]=1).</td> </tr> <tr> <td> </td><td valign="top"><li><b>ADDR1_RD</b></li></td> <td>: This bit is set whenever the CPU performs a read access at the BRKx_ADDR1 address (valid if RANGE_MODE=0 and ACCESS_MODE[0]=1).</td> </tr> <tr> <td> </td><td valign="top"><li><b>ADDR0_WR</b></li></td> <td>: This bit is set whenever the CPU performs a write access at the BRKx_ADDR0 address (valid if RANGE_MODE=0 and ACCESS_MODE[1]=1).</td> </tr> <tr> <td> </td><td valign="top"><li><b>ADDR0_RD</b></li></td> <td>: This bit is set whenever the CPU performs a read access at the BRKx_ADDR0 address (valid if RANGE_MODE=0 and ACCESS_MODE[0]=1).</td> </tr> </tbody></table> <a name="2.4.3 BRKx_ADDR0"></a> <h3>2.4.3 BRKx_ADDR0</h3> This 16 bit read-write register holds the value which is compared against the address value currently present on the program or data address bus. After a POR, this register is set to 0x0000. <br><br> <table border="1"> <tbody><tr align="center"> <td rowspan="2"><b><small>Register Name</small></b></td> <td rowspan="2"><b><small>Address</small></b></td> <td colspan="16"><b><small>Bit Field</small></b></td> </tr> <tr align="center"> <td><small>15</small></td><td><small>14</small></td> <td><small>13</small></td><td><small>12</small></td> <td><small>11</small></td><td><small>10</small></td> <td><small> 9</small></td><td><small> 8</small></td> <td><small> 7</small></td><td><small> 6</small></td> <td><small> 5</small></td><td><small> 4</small></td> <td><small> 3</small></td><td><small> 2</small></td> <td><small> 1</small></td><td><small> 0</small></td> </tr> <tr align="center"> <td><small>BRKx_ADDR0</small></td> <td><small>0x0A, 0x0E, 0x12, 0x16</small></td> <td colspan="16"><font size="-5">BRK_ADDR0[15:0]</font></td> </tr> </tbody></table> <br> <table border="0"> <tbody><tr> <td> </td><td valign="top"><li><b>BRK_ADDR0</b></li></td> <td>: Value compared against the address value currently present on the program or data address bus.</td> </tr> </tbody></table> <a name="2.4.4 BRKx_ADDR1"></a> <h3>2.4.4 BRKx_ADDR1</h3>This 16 bit read-write register holds the value which is compared against the address value currently present on the program or data address bus. After a POR, this register is set to 0x0000. <br><br> <table border="1"> <tbody><tr align="center"> <td rowspan="2"><b><small>Register Name</small></b></td> <td rowspan="2"><b><small>Addresses</small></b></td> <td colspan="16"><b><small>Bit Field</small></b></td> </tr> <tr align="center"> <td><small>15</small></td><td><small>14</small></td> <td><small>13</small></td><td><small>12</small></td> <td><small>11</small></td><td><small>10</small></td> <td><small> 9</small></td><td><small> 8</small></td> <td><small> 7</small></td><td><small> 6</small></td> <td><small> 5</small></td><td><small> 4</small></td> <td><small> 3</small></td><td><small> 2</small></td> <td><small> 1</small></td><td><small> 0</small></td> </tr> <tr align="center"> <td><small>BRKx_ADDR1</small></td> <td><small>0x0B, 0x0F, 0x13, 0x17</small></td> <td colspan="16"><font size="-5">BRK_ADDR1[15:0]</font></td> </tr> </tbody></table> <br> <table border="0"> <tbody><tr> <td> </td><td valign="top"><li><b>BRK_ADDR1</b></li></td> <td>: Value compared against the address value currently present on the program or data address bus.</td> </tr> </tbody></table> <a name="3. Debug Communication Interface: UART"></a> <div style="text-align: right;"><a href="#TOC">Top</a></div> <h1>3. Debug Communication Interface: UART</h1>With its UART interface, the openMSP430 debug unit can communicate with the host computer using a simple RS232 cable (connected to the <a href="http://opencores.org/project,openmsp430,core#2.1.5%20Pinout">dbg_uart_txd</a> and <a href="http://opencores.org/project,openmsp430,core#2.1.5%20Pinout">dbg_uart_rxd</a> ports of the IP).<br>Typically, a <a href="http://www.google.com/search?q=usb+to+rs232+converter">USB to RS232</a> or <a href="http://www.ftdichip.com/Products/Cables/USBTTLSerial.htm">USB to serial TTL</a> cable will provide a reliable communication link between your host PC and the openMSP430 (speed being typically limited by the cable length). <a name="3.1 Serial communication protocol: 8N1"></a> <h2>3.1 Serial communication protocol: 8N1</h2> There are plenty tutorials on Internet regarding RS232 based protocols. However, here is quick recap about 8N1 (1 Start bit, 8 Data bits, No Parity, 1 Stop bit):<br> <br> <img src="usercontent,img,1247419201" alt="8N1 Serial Protocol" title="8N1 Serial Protocol"> <br> As you can see in the above diagram, data transmission starts with a Start bit, followed by the data bits (LSB sent first and MSB sent last), and ends with a "Stop" bit. <a name="3.2 Synchronization frame"></a> <h2>3.2 Synchronization frame</h2>After a POR, the Serial Debug Interface expects a synchronization frame from the host computer in order to determine the communication speed (i.e. the baud rate).<br> The synchronization frame looks as following: <br> <img src="usercontent,img,1247420610" alt="Debug Synchronization Frame" title="Debug Synchronization Frame"> <br> As you can see, the host simply sends the 0x80 value. The openMSP430 will then measure the time between the falling and rising edge, divide it by 8 and automatically deduce the baud rate it should use to properly communicate with the host. <br><br> <b>Important note</b>: if you want to change the communication speed between two debugging sessions, the Serial Debug Interface needs to go through a reset cycle (i.e. through the <span style="font-style: italic;">reset_n</span> or <span style="font-style: italic;">dbg_en</span> pins) and a new synchronization frame needs to be send. <br> <a name="3.3 Read/Write access to the debug registers"></a> <h2>3.3 Read/Write access to the debug registers</h2> In order to perform a read / write access to a debug register, the host needs to send a command frame to the openMSP430.<br>In case of write access, this command frame will be followed by 1 or 2 data frames and in case of read access, the openMSP430 will send 1 or 2 data frames after receiving the command. <a name="3.3.1 Command Frame"></a> <h3>3.3.1 Command Frame</h3> The command frame looks as following: <br> <img src="usercontent,img,1247427400" alt="Debug Command Frame" title="Debug Command Frame"> <br> <table border="0"> <tbody><tr> <td> </td><td valign="top"><li><b>WR</b></li></td> <td>: Perform a Write access when set. Read otherwise.</td> </tr> <tr> <td> </td><td valign="top"><li><b>B/W</b></li></td> <td>: Perform a 8-bit data access when set (one data frame). 16-bit otherwise (two data frame).</td></tr><tr> </tr> <tr> <td> </td><td valign="top"><li><b>Address</b></li></td> <td>: Debug register address.</td></tr><tr> </tr> </tbody></table> <a name="3.3.2 Write access"></a> <h3>3.3.2 Write access</h3> A write access transaction looks like this: <br> <img src="usercontent,img,1247428987" alt="Debug Write Transaction" title="Debug Write Transaction"> <a name="3.3.3 Read access"></a> <h3>3.3.3 Read access</h3> A read access transaction looks like this: <br> <img src="usercontent,img,1247429086" alt="Debug Read Transaction" title="Debug Read Transaction"> <a name="3.4 Read/Write burst implementation for the CPU Memory access"></a> <h2>3.4 Read/Write burst implementation for the CPU Memory access</h2>In order to optimize the data burst transactions for the UART, read/write access are not done by reading or writing the MEM_DATA register.<br> Instead, the data transfer starts immediately after the MEM_CTL.START bit has been set. <a name="3.4.1 Write Burst access"></a> <h3>3.4.1 Write Burst access</h3> A write burst transaction looks like this: <br> <img src="usercontent,img,1247430408" alt="Debug Write Burst Transaction" title="Debug Write Burst Transaction"> <a name="3.4.2 Read Burst access"></a> <h3>3.4.2 Read Burst access</h3> A read burst transaction looks like this: <br> <img src="usercontent,img,1247430449" alt="Debug Read Burst Transaction" title="Debug Read Burst Transaction"> <div style="text-align: right;"><a href="#TOC">Top</a></div> </body></html>
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