ESP32 Forum

Posted: **Sun May 22, 2022 10:06 pm**

Hi
i am trying to implement a project that involves IRDA data communication.
In all the docs it is stated, that the ESP32 UART can be configured to act as IRDA encoder/decoder and directly control an IRDA tranceiver. Based on that I did my design.
Now either me or the ESP-Software have some flaws.
I got inspired by this post: viewtopic.php?t=2766
and did this:

void setup() {
pinMode(0,OUTPUT);
digitalWrite(0, HIGH);
Serial.begin(115200);
USBSerial.begin(115200);
WRITE_PERI_REG( 0x3FF40020 , READ_PERI_REG(0x3FF50020) | (1<<16 ) | (1<<10 ) ); //UART_IRDA_EN + UART_IRDA_TX_EN
for (uint8_t n = 0;n<10; n++) {
Serial.printf("UART-OK[%d] ", n);
USBSerial.printf("USB-OK[%d] ", n);
delay(500);
if (!(n&0x7)){
Serial.println();
USBSerial.println();
}
}

As soon as I include the WRITE_PERI_REG call, the result is a boot loop, no mater what I try:

ESP-ROM:esp32c3-api1-20210207
Build:Feb 7 2021
rst:0x3 (RTC_SW_SYS_RST),boot:0xa (SPI_FAST_FLASH_BOOT)
Saved PC:0x403818be
SPIWP:0xee
mode:DIO, clock div:1
load:0x3fcd6100,len:0x438
load:0x403ce000,len:0x90c
load:0x403d0000,len:0x2358
SHA-256 comparison failed:
Calculated: a9753a4fc647c6545c1b919ef08db429130a48592727edca270f1e5a3da0d0a9
Expected: 3bf6ef2cf3b9eefcd4b3c70cc5d1ce5138292d101a5cb1d5db6fbebf081b0a19
Attempting to boot anyway...
entry 0x403ce000

What is wrong here? A bug? Me?
Any input highly appreciated.
Regards
Thomas

Posted: **Mon May 23, 2022 5:49 am**

That bit of code contains a peripheral address that is valid for the original, non-C3 ESP32 only. (Also, it may be wrong, it reads from 0x3FF50020 but writes to 0x3FF40020...)

I don't know Arduino good enough, but you could try this:

Code: Select all

#include "soc/uart_struct.h" //put this at the top of your program

//change the WRITE_PERI_REG line to this:
UART0.conf0.irda_en=1;
UART0.conf0.irda_tx_en=1;

If it works, it should also make your code compatible with most other ESP32s.

Posted: **Mon May 23, 2022 7:02 am**

Looks like the equivalent register is at 0x6001_0020 for UART1 in ESP32-C3 and the bytes are packed the same as ESP32.

Posted: **Mon May 23, 2022 7:04 am**

But the API is better

Posted: **Mon May 23, 2022 7:28 am**

Ii's a good day today.
"UART0.conf0.irda_en=1"... works well. I can now continue with my project.

: timing.PNG (38.88 KiB) Viewed 2823 times

The image shows what happens on the lines. Middle is the the sender, top the receiver and the lower is a toggle after Serial.flush().
All perfect.
I think I just need to "UART0.conf0.irda_tx_en=0;" after Serial.flush() when I want to switch to RECEIVE after send is complete, right?
Thank you for making may day...
Best regards
Thomas

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