Tool/software:
Using your ADS8684A4 channel AD acquisition chip, we are experiencing the following problems.
Hardware using internal reference voltage, measured as 4.086V
1. Configuration range of 0-2.5 × VREF, when the input voltage input is less than 1.5V, SPI read the collected voltage value is 0, 1.5V-10V collection is normal.
2. Configuration range ± 2.5 × VREF, when the input voltage input is less than -7.117V, SPI read the collected voltage value is 0, -7V - +10V collection is normal.
3. Including other ranges ± 1.25 × VREF, 0-1.25 × VREF, ± 0.625 × VREF, 0-0.625 × VREF have this common problem, the measurement range of less than 15% of the value can not be measured, the measurement range of more than 15% of the value of the value can be measured.
The schematic diagram is as follows
Using SPI communication, the ALARM and SPI are connected to the MCU via an isolation chip.
The software is as follows:
Set the acquisition range of each channel, and set four channels for automatic acquisition.
Polling reads four channel AD values
