I'm trying to read position information over SPI using EVAL-AD2S1210EDZ. In this process I'm using microchip dsPIC33FJ32MC204 for SPI communication.
Eval Board Config: Res0:1; Res1:0 (16 bit) and A0:0; A1:0 to give position information all the time. Communication mode: Serial
There are two cases I tried.
Case 1: Framed SPI mode, the mode in which Clock Pulse will be continuously sent regardless of the data transmission. The position information is coming correct varying from 0 - 65535.
Problem: Problem with this case is the position variation from 0 to 65535 is happening over 90° instead of 360°. Could some one point out where the error is?
Case 2: Normal SPI mode, the mode in which Clock Pulse is transmitted only when the data is required. Here the position information varies from 32767 to 65535. 0-32767 is completely missing. Why is this so?
If the attached waveforms are observed, Case 1 though giving reliably right information is taking about 19 Clock Pulses. And in case 2, it is 16 pulses. Is there some thing I'm missing? Please highlight.
Update1: I'm using 4x resolver, which actually outputs Sin4θ and Cos4θ. So it gives 4 NM pulses for one complete mechanical rotation; meaning it should give 4 cycles of 0-65535. But I see 16 cycles as such.