OPA (Operational Amplifier / Comparator)

[fulda1]

Hi,

I'm playing with OPA and CH32V203. It seems, that ch32v20x_opa.h is not included by default. That is little surprise as rest of hardware headers are. So, I must add #include "ch32v20x_opa.h" to my *.ino file. That is not nice, as it become "processor dependent".

Jindra

[maxint-rd]

Isn't there a generic processor-independent header file. If not, I guess there should be...

I've not yet tested OPA on any CH32 and could really find a clear V003 example for the Arduino core when I looked. Whenever you have something working, could you share some code and also indicate what you connect to which pin?
(The whole concept of using the OPA is currently beyond my level of experience, but I'd like to use it to do some more precise current measurement).

[fulda1]

Agree, that header should be included.

Let me describe my project. It is simple. Have serial communication interface up to 15V with break in 4V. Interface is called LocoNet and is used in model railways. Some projects available for example: https://mrrwa.org/loconet-interface/
My one is shifted for 3V3 logic, so break is in 2V. It mean, negative input powered by 2V and positive input by signal (after some resistor dividers).
Output of OPA (in comparator mode) is same as UART2 Rx, si, instant pin sharing should work.

Piece of code I have so far: (now working on USART init and Tx part, that is little complicated, as it should realize CSMA-CD on serial port)

#include "ch32v20x_opa.h"

// ...

void OPA1_Init( void )
{
  // PA6 - OPA1_CH1N
  // PB0 - OPA1_CH1P
  // PA3 - OPA1_OUT0 (USART2_RX)
  OPA_InitTypeDef  OPA_InitStructure = {0};

  pinMode(PB0, INPUT);
  pinMode(PA6, INPUT);

  OPA_InitStructure.OPA_NUM = OPA1;
  OPA_InitStructure.PSEL = CHP1;
  OPA_InitStructure.NSEL = CHN1;
  OPA_InitStructure.Mode = OUT_IO_OUT0;
  OPA_Init( &OPA_InitStructure );
  OPA_Cmd( OPA1, ENABLE );

}