Hi,
We have been using the ADS1220 for a wheatstone bridge sensor and now we would like to do temperature measurements using the internal temperature sensor as well. However, we found that data received from the ADS1220 is mixed up so that temperature measurements are bridge values and that bridge sensor measurements have an intermittently wrong value, which we suspect is a temperature value.
The implementation we would like is: Bridge measurement every 15millisec, Int Temp measurements every 1sec. During Int Temp measurement, Bridge measurement is paused.
Configuration Registers are as follows:
- Register: 00 / 01 / 02 / 03
- Bridge: 3E / 40 / 88 / 00
- Int Temp: 3E / 42 / 88 / 00
Psuedo-code for sampling the Bridge Sensor and Int Temp sensor is as follows:
- Send All Configuration Registers
- Send Start Command
- Wait for Data Ready
- Read Data Register
- Power Down
- Compute output
When we run each sample individually (ie. Bridge measurement every 15millisec only -or- Int Temp every 1 sec only), the values received are correct. However, when ran together so that the ADS1220 has to switch inputs, it mixes up the values. We monitored DRDY pin and it seems that there is a 100millisec gap when the switch occurs.
Is our setup the ideal way to handle the switch between Bridge and Int Temp? Is there a way to ensure that the RDATA is the right value we want? (ie. perhaps read back the Configuration registers?)
Thanks,
