• 状态 TI Thinks Resolved
  • 回复 4 回复
  • 答案 1 答案
  • 订户 15 订户
  • 视图 141 视图
  • 用户 0 会员在此处
选项
选项
相关

ADS122S14: ADS122S14:ADS122S14 No SPI Response After Enabling IDAC 200μA Output

? ?
Prodigy 40 points

Part Number: ADS122S14
Other Parts Discussed in Thread: MSPM0G3507,

Hardware setup:

MCU: MSPM0G3507

ADC: ADS122S14

problem：The initialization using the DEMO program can communicate with the ADC. However, after modifying the initialization, I was unable to communicate with the ADC, and even when I used the DEMO program for initialization again, I still couldn't communicate with the ADC. Has the ADC failed?I need design a three-wire PT100 RTD measurement and two IDAC current source.Could you please help me analyze what caused this? 

demo progrom:

demo.png

my progrom:

myself.png

  • 0
    TI__Mastermind 42040 points

    Hi,

    Thank you for contacting TI China E2E forum and choosing our products as part of your solution.

    Regarding your query, please give us some time to confirm this issue.

  • 0 回复 Links
    Prodigy 40 points

    I found that by enabling only IDAC1, the communication seems to be working properly.

  • 0 回复 ? ?
    Prodigy 40 points 

    	//IDAC_MUX_CFG_ADDRESS = 0x0E--> IDAC unit current select 10uA, IDCA1 is AIN6.
	writeSingleRegister(IDAC_MUX_CFG_ADDRESS, IDAC_MUX_CFG_IUNIT_10MUA | IDAC_MUX_CFG_I1MUX_AIN6);

	//IDAC_MAG_CFG_ADDRESS = 0x0D--> IDAC1 current is 90x unit(90*10uA = 900uA).
	writeSingleRegister(IDAC_MAG_CFG_ADDRESS, IDAC_MAG_CFG_I1MAG_90XIUNIT);

	//DIGITAL_CFG_ADDRESS = 0x0A--> Enables the STATUS header.
	writeSingleRegister(DIGITAL_CFG_ADDRESS, DIGITAL_CFG_STATUS_EN_ENABLED);

	//REFERENCE_CFG_ADDRESS = 0x09--> enable REF buffer.
	writeSingleRegister(REFERENCE_CFG_ADDRESS, /*REFERENCE_CFG_REFP_BUF_EN_ENABLED |*/ REFERENCE_CFG_REF_VAL_2);

	//MUX_CFG_ADDRESS = 0x07--> Positive input is AIN0, Negative input is AIN1.
	writeSingleRegister(MUX_CFG_ADDRESS, MUX_CFG_AINP_AIN0 | MUX_CFG_AINN_AIN1);

	//DATA_RATE_CFG_ADDRESS = 0x06--> fDATA = 25SPS (independent of speed mode).
	writeSingleRegister(DATA_RATE_CFG_ADDRESS, DATA_RATE_CFG_FLTR_OSR_FSUBDATASUB25SPS);

	//DEVICE_CFG_ADDRESS = 0x05--> Continuous-conversion mode.
	writeSingleRegister(DEVICE_CFG_ADDRESS, DEVICE_CFG_CONV_MODE_CONTINUOUSCONVERSIONMODE);
    this is my progrom. 

  • 0 回复 ? ?
    TI__Mastermind 42040 points

    Thank you for your question regarding the ADS122S14 SPI communication.

    When enabling the 200µA IDAC output, please verify the following operating conditions:

    1. IDAC Compliance Voltage: The voltage at the IDAC pin must remain below (AVDD - 0.3V). If your load resistance is too high, the IDAC cannot maintain the programmed current, which may cause the device to become unresponsive.

    2. Load Resistance Calculation: For 200µA IDAC with typical AVDD = 3.3V, maximum load resistance ≈ (3.0V / 200µA) = 15kΩ. Please check if your load exceeds this limit.

    3. Operating Mode: Verify the device is in normal operating mode, not standby or power-down, as SPI communication requires active operation.

    Troubleshooting steps:

    • Measure the voltage at your IDAC pin during operation
    • Reduce load resistance if voltage approaches AVDD
    • Verify SPI communication works with IDAC disabled to isolate the issue

    Please refer to the ADS122S14 datasheet Section 7.3.8 (IDAC) for detailed specifications and operating conditions.