Recently, I am using S32K144 (2ADC module with a total of 32 AD channels) to realize the function of AD multiplexing. But I am facing a complex requirement.
need:
The 2 AD channels are sampled at the middle point of the 1 PWM (frequency 1KHz, duty cycle varies with function).
21-way AD polling sampling, preferably 5ms, 10ms is also fine.
What is fixed is:
1. FTM (INIT trigger in CPWM mode) - "TRGMUX;
2. The 21-way AD polling uses PDB->AD;
There are two ideas:
1. FTM-"TRGMUX-"PDB-"AD Put two ADs with special requirements into R0 of ADC0 and R0 of ADC1 respectively, this should be feasible, but AD polling depends on FTM's init_trg, and the sampling frequency is 1ms.
2. FTM->TRGMUX->Two special ADs; LPIT interrupt (software-trigger)->PDB->23 ADs. Two of the special ADs are still placed first. These two modes are switched in the 1ms interrupt of LPIT.
Personally, I would like to try the second method, but the problem is that I don't know how fast the switching of the ADC's pre-trigger source and trigger source in the SIM will affect the AD convert process.
最近我在用S32K144（2ADC 模块 共 32 AD通道)实现AD多路采集的功能。 但是我面对一个复杂的需求。
需求：
2路AD通道在1路PWM（频率1KHz，占空比随功能变化）的中间点采样。
21路AD轮询采样，最好是5ms,10ms也行。
固定的是：
1、FTM（CPWM模式的INIT触发）-》TRGMUX；
2、21路的AD轮询使用PDB-》AD；
现有两种思路：
1、FTM-》TRGMUX-》PDB-》AD 分别把两路特殊要求的AD放到ADC0的R0和ADC1的R0，这样应该是可行的，但是AD轮询依赖到FTM的init_trg 上 ，而且采样频率是1ms。
2、FTM-》TRGMUX-》两路特殊AD； LPIT中断（software-trigger）-》PDB-》23路AD。其中两路特殊AD仍然放到最先。 这两种模式在LPIT的1ms中断中切换。
个人很想试一试第二种方法，但是问题是，并不知道在SIM中对ADC的预触发源和触发源切换有多快，会对AD convert 过程产生什么影响。
