Conversion of some Serial UART registers from R3 to R4

Official Hardware UNO Family UNO R4 WiFi
1

Hi - Having some trouble converting this code from an Arduino Uno R3 to an R4. It manipulates the USART Control and Status Register B to set for 9-bit operation (changes the parity bit). Looking for the equivalent calls that are compatible with the R4:

  UCSR1B = 0b10011101;
  Serial1.write(0x80);
  delay(20);
  Serial1.write(0x81);
  UCSR1B = 0b10011100;

Getting UCSR1B was not declared in this scope.

I've looked at the CPU datasheet but I am not finding what I need. Any help would be appreciated. Thanks!

2

A much more sensible approach would be to learn how to receive 9 bit serial data on the relevant R4 processor, since it and its peripherals have essentially no relationship to those of the Uno R3.

3

If you're just looking to send/receive 8 bits with parity, you might want to try out Serial1.begin(baud, SERIAL_8E1); or Serial1.begin(baud, SERIAL_8O1);

4

The protocol of the device I am communicating with expects the 9th parity bit to be set to 1 (mark parity) when sending the data and then set to 0 (space parity) when done; example from c#:

  Byte[] GenPoll = { 0x80, 0x81 };
  SerialPort1.Parity = Parity.Mark;
  SerialPort1.Write(GenPoll, 0, 1);   // sends  0x80 gen pol to all machines  they wake up and listen for their address OR'ed with 0x80
  Thread.Sleep(20); gives the machine time to clear responses from its buffer (prevents duplicate responses)
  SerialPort1.Write(GenPoll, 1, 1); // sends out poll to mahne with address of 1
  SerialPort1.Parity = Parity.Space;

I have been digging through the R4 code - hardwareserial, serial, serialUSB and it does not seem like it supports mark or space parity as written. Nor do I see any UART registers I can manipulate like on the R3.

6

Thank you - that got me closer. I think the command I need looks something like this:

SCI1.TDRHL.BYTE.TDRH = 0xFE; (this will set the 9th bit to 0)

However - I am still getting error: 'SCI1' was not declared in this scope

What reference/include am I missing?

8

When you say 'Set it for 9-bit'; I am not sure how to do that. The hardwareserial library does not support 9bit mode. So if I do a Serial1.begin(19200,SERIAL_9N1) it fails; if I attempt to update hardwareserial with a definition for SERIAL_9N1 the R4 crashes when trying to execute that line.

I've looked over the docs but I'm not very familiar with low-level manipulation of these registers. Any sample code you could share?

10

Hello, any news regarding this ?
I also would like to have 9-bit support on UNO R4 !!
Today I can only use 8bit data. Such as "Serial1.begin(9600,SERIAL_8N1)".
N/E/O works fine , but when setting for 7-bit in Serial.begin it compiles but nothing is transmitted. When trying with9-bit. I get a compilation error ...not declared in this scope.
I really think when starting with a new UNO R4, you should be able to use 5-9 bit data.
Today I use Teensy 4.0 where all this works fine (after a small edit in "hardwareSerial.h".
/

12

@marcdavis
You could say frame length instead of (confusing) 9-bit operation.

Start Bit:  1
Data Bits:  7 or 8
Parity Bit: Odd or Even or None
Stop Bit:   1 or 2
14

9bit support is a much bigger project than just adding the various smaller configuration combination working. Unless you have a working 9bit Serial class for AVR or some other chip, it means re-writing significant portions of the HardwareSerial class (and introducing incompatibilities with Stream (non-UART Serial-like interfaces.))

1 Like
15

So I am creeping closer to my answer; I have a conceptual example of what I need; but I am missing the correct includes from the Renesas SSP for the RA4M1. I downloaded what I think is the SSP from their site but can't find the right set of files to include. Can anyone help me move this further?

Example code:

#include "r_sci_uart.h"

/* UART control structure */
static sci_uart_instance_ctrl_t g_uart_ctrl;

void setup() {
  hardware_init();
}

void loop() {
  setNinthBit();  // Set the 9th bit
  R_SCI_UART_Write(&g_uart_ctrl, &byte, 1);
  resetNinthBit();  // Reset the 9th bit
  delay(20);
  setNinthBit();  // Set the 9th bit again if needed
  R_SCI_UART_Write(&g_uart_ctrl, &byte, 1);
  resetNinthBit();  // Reset the 9th bit
}

void hardware_init(void) {
  /* Initialize hardware here, including UART configuration for RA4M1 */

  /* Initialize UART control structure */
  R_SCI_UART_Open(&g_uart_ctrl, &g_uart_cfg);
}

void setNinthBit() {
  /* Set the 9th bit (T8) for SCI communication on RA4M1 */
  g_uart_ctrl.p_reg->SCMR |= SCI_SCIF_SCMR_T8;
}

void resetNinthBit() {
  /* Reset the 9th bit (T8) for SCI communication on RA4M1 */
  g_uart_ctrl.p_reg->SCMR &= ~SCI_SCIF_SCMR_T8;
}

Getting a variety of compile errors like: Compilation error: 'g_uart_cfg' was not declared in this scope.

16

Did you ever get this working? I am also working on a 9bit machine and need a solid way to talk with it.

17

I have 9-bit tx working on the new Uno r4 wifi and Minima. It takes a couple of tiny tweaks to the core. The core and the boards already support it; we just need to allow access to it by adding a few definitions and a case. I have submitted my code updates as pull requests to the API and Core repos. I am also working on a forum post that outlines the changes needed and how to use them. It is amazing to have true 9-bit functions.

19

Vashadow. In your pull request did you also include support for 7bit?

My question is because there is another thread here about 7 bit support.
Solved with adding lines to the ”Serial.cpp” filé.