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[/] [open8_urisc/] [trunk/] [VHDL/] [o8_rtc.vhd] - Rev 210

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210 Modified the timers to reset on new interval write. This avoids an issue in the original design where the timer had to reach zero before updating, potentially causing unwanted interrupts.
Also added a flag to the CPU to allow interrupts to be processed sequentially based on the state of the I bit. This one is set to false by default, as it is a significant change in interrupt behavior. Long, and reentrant, ISRs can clear the I bit prematurely to allow themselves to be interrupted.
Lastly, added the I bit to the exported flags for possible use in memory protection schemes.
jshamlet 1701d 17h /open8_urisc/trunk/VHDL/o8_rtc.vhd
209 Fixed an issue in the PIT timer that caused an immediate interrupt on interval write,
Fixed an issue in the epoch timer that resulted in a spurious interrupt due to extra LSB's being set by default in the set point register,
While cleaning elsewhere, founding a spacing issue in the CPU HDL,
Added a 4k ROM and MW core.
jshamlet 1702d 06h /open8_urisc/trunk/VHDL/o8_rtc.vhd
194 Cleaned up licensing sections jshamlet 1710d 12h /open8_urisc/trunk/VHDL/o8_rtc.vhd
191 Cleaned up comments, added back the OPEN8_NULLBUS constant, and added some new modules for ADCs and LCD displays.
Also made the button input module more configurable by moving the debounce code to a separate entity and using generics to instantiate it.
jshamlet 1710d 13h /open8_urisc/trunk/VHDL/o8_rtc.vhd
190 Fixed a bug in CPU where RTI/RTS wasn't idling the instruction cache, causing intermittent failures where RTI would execute as RTS, corrupting the stack;
Fixed a bug in the real-time clock where the uSec tick generator would stop if the PIT timer value was left/set to 0x00.
jshamlet 1722d 10h /open8_urisc/trunk/VHDL/o8_rtc.vhd
189 Merged changes from private repository,
added ceil_log2 function to Open8_pkg, since it is used to calculate RAM vectors,
cleaned up comments and removed local copies of the ceil_log2 function from peripherals.
jshamlet 1723d 11h /open8_urisc/trunk/VHDL/o8_rtc.vhd
177 Fixed comments in RTC module jshamlet 3055d 13h /open8_urisc/trunk/VHDL/o8_rtc.vhd
176 Fixed documentation errors,
Modified uSec_Tick such that it is always generated regardless of the interval.
jshamlet 3060d 11h /open8_urisc/trunk/VHDL/o8_rtc.vhd
172 General code cleanup jshamlet 3255d 11h /open8_urisc/trunk/VHDL/o8_rtc.vhd
168 Simplified write data path logic,
Converted RTC to packed BCD,
Corrected several bugs in real time clock component,
jshamlet 4089d 08h /open8_urisc/trunk/VHDL/o8_rtc.vhd
167 Updated CPU model; Pipelined ALU control signals to improve fMAX, corrected issue with interrupt controller priority not being obeyed, fixed bug in auto-indexing instructions where the upper register wasn't being properly incremented, cleaned up code to make the processor model easier to follow.
Added several useful modules that use the Open8 bus.
jshamlet 4097d 06h /open8_urisc/trunk/VHDL/o8_rtc.vhd

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