We are using the ADS1248 in our project.
I'm trying to debug my ADS1248 driver. Communication via SPI seems to be OK.
The ADS1248 is connected to following supplies: AVDD = +5V DVDD = +3.3V AVSS and DVSS = 0V VREF_P1 = 2.5V VREF_N1 = 0V (VREF_P0/VREF_N0 are not important for now)
I can read and write all the registers. I also tested the SELFOCAL and other commands.
To understand an test the device I first tried to measure AVDD and DVDD via 6 and 7 in MUXCAL2:0 REFSELT1:0 = 01
But then I try to get some conversion data I get unusable values. After programming all the registers I apply a 1ms START Pulse.
After finding DRDY low I sent RDATA NOP NOP NOP commands reading back data at the same time.
Here you can find the register read back before the START pulse and the Value I read back.
Info: Readback registers 0 .. 14: 00 00 2F 00 40 AA FC 80 09 40 86 FF 00 00 00
Info: DATA: 03 03 59 F7
Info: DATA: 03 03 59 97
Info: Readback registers 0 .. 14: 00 00 2E 00 40 AA FC 80 09 40 86 FF 00 00 00
Info: DATA: 2F 2F 11 14
Info: DATA: 2F 2F 11 04
As you can see I read back data twice for testing. After the first RDATA + NOPs I gave a second START Pulse.
I wonder why The first byte is send out without the RDATA command completely sent.
The value 035997 was read back for the DVDD 3.3V
The value 2F1104 was read back for the AVDD 5V
The 2.5V VREF has been used.
Are the registers set up OK for the System Monitor Test?
The data don't seem to make any sense. Is the data OK, but my calculation not?
I thought LSB has the value of VREF/ 2^23-1 ~ 296nV
I also measure external values also with no sense making values. But I first want to fix the System Monitor Problem.
Thanks for your help.
Michael
