I used to work with AD7705. Now I need to configure 10 boards with AD770test AD7707.RAR7. I am getting wrong data from the chip. What am I doing wrong?
Sorry for the late response. I would like to clarify if your voltage reference is 2.5V? And whether you used a probe to measure your 100mV and 141mV AIN?
Also, can you provide a digital interface (scope shot) of your setup and a read back register values? Thank you.
This archive contains the necessary information.
Oscilloscope: 1V/div, 1mS/div
I don't understand why there is only the low byte (high byte=0) in the data register. When reading, it should be approximate:
AIN1 - 139 mv (gain=16) = E1 XX
AIN3 - 2 V = (gain=1) = CC XX
Here is the table.
I have a 1-channel oscilloscope. I will try to use a logic analyzer. But there should be no problems with the timings. I used to work with AD7705 and everything works there. There is the same interface. I used those routines here. In addition, the SETUP and CLOCKXLS registers are written and read normally. And this means that the timings are correct.
Can you share what's the difference between your AD7705 design and this new AD7707 design?
The two devices have different input channels. The AD7707 has a high level analog input voltage referenced to HICOM with a VBIAS voltage.
Looking at your AD7707 schematic, the VBIAS was also generated from the VREF but I am not sure what's the purpose of this bias if the HICOM is unused?
Have you tried to probe your REFIN pins? Is it exactly 5V?