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ldalmasso |
# PmodAD2Driver
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Pmod AD2 Driver for the 4 Channels of 12-bit Analog-to-Digital Converter AD7991. The communication with the ADC uses the I2C protocol. User can specifies the I2C Clock Frequency (up to 400 kHz with the Fast Mode).
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## Usage
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User specifies inputs: I2C mode (i_mode), ADC Slave Address (i_addr), Configuration Byte (i_config_byte, write mode only) and the Last Read Cycle trigger (i_last_read, read mode only).
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The i_enable signal can be triggered (set to '1') to begin transmission.
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When started, the PmodAD2Driver executes the complete operation cycle (configurations or ADC conversions) independently of the new i_enable signal value.
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At the end of the operation cycle, if the i_enable signal is still set to '1', the PmodAD2Driver executes the operation again with the current inputs.
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The o_ready signal (set to '1') indicates the PmodAD2Driver is ready to process new operation. The o_ready signal is set to '0' to acknowledge the receipt.
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The o_ready signal is set to '0' to acknowledge the receipt.
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In Write mode, the PmodAD2Driver writes the Configuration byte into the ADC register and stop the transmission.
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In Read mode, the PmodAD2Driver always reads 2-byte ADC conversion values channel-by-channel (according to ADC configuration).
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The ADC value (o_adc_value) is available when its validity signal (o_adc_valid) is asserted.
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In Read mode, while the i_last_read is NOT set to '1', the PmodAD2Driver execute the read operation.
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ADC AD7991 has 2 I2C Addresses:
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AD7991-0: 010 1000
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AD7991-1: 010 1001
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Configuration Register (8-bit Write Only)
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| D7 | D6 | D5 | D4 | D3 | D2 | D1 | D0 | Bit |
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|-----|-----|-----|-----|---------|------|-----------------|------------|-----|
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| CH3 | CH2 | CH1 | CH0 | REF_SEL | FLTR | Bit Trial delay | Sample delay | Description |
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| 1 | 1 | 1 | 1 | 0 | 0 | 0 | 0 | Default Value |
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Configuration Register MSB Description
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| D7 | D6 | D5 | D4 | Analog Input Channel |
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|----|----|----|----|----------------------|
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| 0 | 0 | 0 | 0 | No channel selected |
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| 0 | 0 | 0 | 1 | Convert on VIN0 |
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| 0 | 0 | 1 | 0 | Convert on VIN1 |
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| 0 | 0 | 1 | 1 | Sequence between VIN0 and VIN1 |
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| 0 | 1 | 0 | 0 | Convert on VIN2 |
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| 0 | 1 | 0 | 1 | Sequence between VIN0 and VIN2 |
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| 0 | 1 | 1 | 0 | Sequence between VIN1 and VIN2 |
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| 0 | 1 | 1 | 1 | Sequence among VIN0, VIN1, and VIN2 |
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| 1 | 0 | 0 | 0 | Convert on VIN3 |
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| 1 | 0 | 0 | 1 | Sequence between VIN0 and VIN3 |
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| 1 | 0 | 1 | 0 | Sequence between VIN1 and VIN3 |
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| 1 | 0 | 1 | 1 | Sequence among VIN0, VIN1, and VIN3 |
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| 1 | 1 | 0 | 0 | Sequence between VIN2 and VIN3 |
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| 1 | 1 | 0 | 1 | Sequence among VIN0, VIN2, and VIN3 |
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| 1 | 1 | 1 | 0 | Sequence among VIN1, VIN2, and VIN3 |
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| 1 | 1 | 1 | 1 | Sequence among VIN0, VIN1, VIN2, and VIN3 |
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Conversion Result Register (16-bit Read Only)
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| D15 | D14 | D13 | D12 | D11 | D10 | D9 | D8 | D7 | D6 | D5 | D4 | D3 | D2 | D1 | D0 |
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|-----|-----|-------|-------|-----|-----|----|----|----|----|----|----|----|----|----|----|
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| 0 | 0 | CHID1 | CHID0 | MSB | B10 | B9 | B8 | B7 | B6 | B5 | B4 | B3 | B2 | B1 | B0 |
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## Signal Generator Pin Description
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### Generics
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| Name | Description |
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| ---- | ----------- |
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| sys_clock | System Input Clock Frequency (Hz) |
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| i2c_clock | I2C Serial Clock Frequency (Standard Mode: 100 kHz, Fast Mode: 400 kHz) |
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### Ports
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| Name | Type | Description |
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| ---- | ---- | ----------- |
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| i_sys_clock | Input | System Input Clock |
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| i_enable | Input | Module Enable ('0': Disable, '1': Enable) |
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| i_mode | Input | Read or Write Mode ('0': Write, '1': Read) |
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| i_addr | Input | ADC Address (7 bits) |
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| i_config_byte | Input | ADC Configuration Byte (8 bits) |
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| i_last_read | Input | Indicates the Last Read Operation ('0': Continue Read Cycle, '1': Last Read Cycle) |
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| o_adc_valid | Output | ADC Read Value Valid ('0': Not Valid, '1': Valid) |
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| o_adc_value | Output | ADC Read Value |
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| o_ready | Output | ADC Ready Status ('0': NOT Ready, '1': Ready) |
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| io_scl | In/Out | I2C Serial Clock ('0'-'Z'(as '1') values, working with Pull-Up) |
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| io_sda | In/Out | I2C Serial Data ('0'-'Z'(as '1') values, working with Pull-Up) |
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