Other Parts Discussed in Thread: ADS1194, , ADS1298, ISOW7841
Hello,
I have a board with ADS1194 chip connected to a controller using a 4-channel isolator. Those 4 channels are used for the SPI communication so there is no access to DRDY pin. The way that is currently used to know when data is ready is polling the MISO signal, CS is kept low all the time and the ADS1194 chip behaves as follows:
- If MISO is currently low, when data is ready, it pulls it high and after ~2 us MISO is pulled low again (#1 on the image)
- If MISO is currently high, when data is ready, it pulls MISO down (#2 on the image)
In the end, controlling the falling edge of MISO signal allows to know when ECG data is ready.
I was planning to use ADS1292 chip for another board which would also use a digital isolator. While testing the device on a prototyping board, I noticed that ADS1292 does not have this kind of behaviour on MISO pin even though I thought it would. (#3 on the image).
Is this the expected behaviour on this chip?