Hi ,
We are using Normal SPI3 of TMS570LS1224PGE (Launch pad board) controller for reading ADC data from ADS1262. The ADC commands like start, read, stop are used to control ADC functionalities instead of start and DRDY pins. For initial checking purpose internal power supply of ADC is used. we are able to read status and checksum ,however ADC values are not as expected. We are reading very less value instead of 1.25V for following configuration.
SPI3 Configuration:
1) Master Mode
2) Internal Clock – 1MHZ
3) Baud Rate – 1MHZ
4) No delay
5) CS HOLD = TRUE
6) SPI3
7) 8 bit mode
8) Polling method
ADC configuration:
1) POWER = 0x01; // VBIAS = OFF, INTREF = ON
2) INTERFACE = 0x05; // SERIAL TIMEOUT DISABLED, STATUS BYTE ENABLED, CHECKSUM ENABLED
3) MODE0 = 0x44; // NORMAL REFERENCE POLARITY, PULSE CONVERSION, CHOP DISABLED, 69us ADDITIONAL DELAY
4) MODE1 = 0x60; // SINC4 (NOT APPLICABLE FOR 38.4kSPS), SENSOR BIAS DISABLED
5) MODE2 = 0x0F; // PGA ENABLED, PGA GAIN = 1, 38400 SPS
6) INPMUX = 0xCC; // ANALOG POWER SUPPLY MONITOR (+), ANALOG POWER SUPPLY MONITOR (-)
7) Other are Default values
8) Command Mode
9) START pin is grounded
Verification done:
1) Configurations are verified by reading back configuration register from ADC.
2) Start and Read commands transmit are verified using oscilloscope.
3) Power to ADC is proper.
Steps:
1) ADC configuration
2) Send Start command
3) Wait
4) Send read command and read adc data.
5) Send stop command
Queries:
1) In command mode is there any special steps needs to be taken care?
2) Is it required to wait for few cycles in between ADC read opcode and ADC data?
Please let us know if more information is required?
Looking forward to hear from you as early as possible.
Thanks in advance.