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CTU (Cross-Triggering Unit) of MPC5675

Question asked by Minmin Zhengzheng on Sep 9, 2018
Latest reply on Mar 27, 2019 by Peter Vlna


I am using a microcontroller model MPC5675 controller. For analog acquisition, I use CTU (Cross-Triggering Unit), and the state variables are obtained through the following peripherals: ADC. The CTU receives incoming input signals from ADC.

The ADC commands list registers (CLRx) provide 8 commands. When CMS = 0, CLRx is in single conversion mode.

FIFO=0-7, that is, 8 channel buffers correspond to 8 CTU acquisition commands, and CH is ADC unit channel number. When I used CTU's ADC to acquire analog quantities, I found a problem in the CTU initialization program. When I used 4 ADC unit channels and 6 ADC unit channels, the signal quality would be very different. Compared with 4, the analog quantity will jump during the acquisition process, and the erroneous data will appear obviously. The following is the program I initialized by CTU:

When I use 4 ADC unit channels, the analog quantities collected are as follows:






When I use 6 ADC unit channels, the analog quantities collected are as follows:


The difference between 4 and 6 ADC unit channel images is that there will be hopping data in one cycle, as shown in the following figure:


                                                      hopping data

I think these error points have something to do with my program.Maybe some registers of CTU of MCU are not set. May I ask why?

thank you