Hello I got some big trouble with the XM1110 in its SPI version.
The first known problem is that after each chip select, the first byte is shifted to the right i.e. (00100100 becomes 00010010), all the other byte are fine.
I’m connected to the XM1110 via a pic32MZ (SPI) there is no problem of configuration and whenever I respect the timing (8ms wait between 255 byte packet) or not I got the issue.
In the screen capture on top you got the general view, in bottom a zoom on data after the CS goes low (the first on the left) with only blank byte (0x0A) where we can see clearly that the first byte has a problem.
C1/Z1 correspond to the CS
C2/Z2 correspond to the MOSI
C3/Z3 correspond to the MISO
C4/Z4 correspond to the CLK
The second big problem I got is the loss of data. I read and decode NMEA data (normally at 5Hz), in my NMEA data I got the different packet: GGA,GSA,GSV,VTG,ZDA (with GPS + Glonass config). SPI is at 600kHz. And the fact is that when I read the UTC time I got the time every 200ms during 5.4s then it cut during 4.8s and so on 5.4s data, 4.8s with no data.
I tried changing the data rate at 10Hz i got 1.2s data for 2.4s no data and at 1Hz 10s data and 17s no data…
I don’t know what makes the XM1110 act like that but the fact that the timing are changing with the rate seems to exclude the acquisition code…
If someone already got the issue or got an idee