Hardware serial

Yucheng · Jun 18, 2024

Hi, I am new to Teensy 4.1 and I am confused on a problem I just ran into.
I am trying to control a motor through another control board, and I have connected teensy 4.1's hardware serial1 pins to the control board. I also got the code package from the seller for operating it. However, the code was originally developed for Arduino uno, not teensy. The main issue is that when the program checks for SerialX.available, it would always return false (in SerialServo.h). I have noticed that the Arduino uno's hardware serial has class of HardwareSerial, while teensy is calling it as HardwareSerialIMXRT. I am not sure if this is the root of the problem. If so, how can I fix it?

SerialServoIDWrite.ino

Code:

#include "include.h"
#include "SerialServo.h"

void setup() {
  Serial1.begin(115200);
  delay(1000);
}

void loop() {
  LobotSerialServoSetID(Serial1, ID_ALL, 3);
  delay(500);
  int id = LobotSerialServoReadID(Serial1);
  Serial.println("");
  Serial.print("new ID:");
  Serial.println(id);
  delay(1000);
}

SerialServo.h

Code:

#include "include.h"

//校验和
byte LobotCheckSum(byte buf[])
{
  byte i;
  uint16_t temp = 0;
  for (i = 2; i < buf[3] + 2; i++) {
    temp += buf[i];
  }
  temp = ~temp;
  i = (byte)temp;
  return i;
}

//解析接收到的数据包信息，并返回
int LobotSerialServoReceiveHandle(HardwareSerial &SerialX, byte *ret)
{
  bool frameStarted = false;
  bool receiveFinished = false;
  byte frameCount = 0;
  byte dataCount = 0;
  byte dataLength = 2;
  byte rxBuf;
  byte recvBuf[32];
  byte i;

  while (SerialX.available()) {
    rxBuf = SerialX.read();
    delayMicroseconds(100);
    if (!frameStarted) {
      if (rxBuf == LOBOT_SERVO_FRAME_HEADER) {
        frameCount++;
        if (frameCount == 2) {
          frameCount = 0;
          frameStarted = true;
          dataCount = 1;
        }
      }
      else {
        frameStarted = false;
        dataCount = 0;
        frameCount = 0;
      }
    }
    if (frameStarted) {
      recvBuf[dataCount] = (uint8_t)rxBuf;
      if (dataCount == 3) {
        dataLength = recvBuf[dataCount];
        if (dataLength < 3 || dataCount > 7) {
          dataLength = 2;
          frameStarted = false;
        }
      }
      dataCount++;
      if (dataCount == dataLength + 3) {

        if (LobotCheckSum(recvBuf) == recvBuf[dataCount - 1]) {

          frameStarted = false;
          memcpy(ret, recvBuf + 4, dataLength);
          return 1;
        }
        return -1;
      }
    }
  }
}
//写入舵机ID
void LobotSerialServoSetID(HardwareSerial &SerialX, uint8_t oldID, uint8_t newID)
{
  byte buf[7];
  buf[0] = buf[1] = LOBOT_SERVO_FRAME_HEADER;
  buf[2] = oldID;
  buf[3] = 4;
  buf[4] = LOBOT_SERVO_ID_WRITE;
  buf[5] = newID;
  buf[6] = LobotCheckSum(buf);
  SerialX.write(buf, 7);
}

//控制舵机转动
void LobotSerialServoMove(HardwareSerial &SerialX, uint8_t id, int16_t position, uint16_t time)
{
  byte buf[10];
  if(position < 0)
    position = 0;
  if(position > 1000)
    position = 1000;
  buf[0] = buf[1] = LOBOT_SERVO_FRAME_HEADER;
  buf[2] = id;
  buf[3] = 7;
  buf[4] = LOBOT_SERVO_MOVE_TIME_WRITE;
  buf[5] = GET_LOW_BYTE(position);
  buf[6] = GET_HIGH_BYTE(position);
  buf[7] = GET_LOW_BYTE(time);
  buf[8] = GET_HIGH_BYTE(time);
  buf[9] = LobotCheckSum(buf);
  SerialX.write(buf, 10);
}


//读取ID
int LobotSerialServoReadID(HardwareSerial &SerialX)
{
  int count = 10000;
  int ret;
  byte buf[6];
 
  buf[0] = buf[1] = LOBOT_SERVO_FRAME_HEADER;
  buf[2] = ID_ALL;  //ID_ALL为254，表示向所有舵机进行广播，可用于读取未知ID的舵机信息
  buf[3] = 3;
  buf[4] = LOBOT_SERVO_ID_READ;
  buf[5] = LobotCheckSum(buf);
  SerialX.write(buf, 6);

 
  while (SerialX.available())
    SerialX.read();

  while (!SerialX.available()) {
    count -= 1;
    if (count < 0)
      return -2048;
  }

  if (LobotSerialServoReceiveHandle(SerialX, buf) > 0)
    ret = (int16_t)BYTE_TO_HW(0x00, buf[1]);
  else
    ret = -2048;
  return ret;
}
//读取舵机位置
int LobotSerialServoReadPosition(HardwareSerial &SerialX, uint8_t id)
{
  int count = 10000;
  int ret;
  byte buf[6];

  buf[0] = buf[1] = LOBOT_SERVO_FRAME_HEADER;
  buf[2] = id;
  buf[3] = 3;
  buf[4] = LOBOT_SERVO_POS_READ;
  buf[5] = LobotCheckSum(buf);
  SerialX.write(buf, 6);
 
  while (SerialX.available())
    SerialX.read();

  while (!SerialX.available()) {
    count -= 1;
    if (count < 0)
      return -2048;
  }

  if (LobotSerialServoReceiveHandle(SerialX, buf) > 0)
    ret = (int16_t)BYTE_TO_HW(buf[2], buf[1]);
  else
    ret = -2048;
  return ret;
}

//读取偏差
int LobotSerialServoReadDev(HardwareSerial &SerialX, uint8_t id)
{
  int count = 10000;
  int ret;
  byte buf[6];

  buf[0] = buf[1] = LOBOT_SERVO_FRAME_HEADER;
  buf[2] = id;
  buf[3] = 3;
  buf[4] = LOBOT_SERVO_ANGLE_OFFSET_READ;
  buf[5] = LobotCheckSum(buf);
  SerialX.write(buf, 6);
 
  while (SerialX.available())
    SerialX.read();

  while (!SerialX.available()) {
    count -= 1;
    if (count < 0)
      return -2048;
  }

  if (LobotSerialServoReceiveHandle(SerialX, buf) > 0)
    ret = (int16_t)BYTE_TO_HW(buf[2], buf[1]);
  else
    ret = -2048;
  return ret;
}
//读取转动范围
int retL;
int retH;
int LobotSerialServoReadAngleRange(HardwareSerial &SerialX, uint8_t id)
{
  int count = 10000;
  int ret;
  byte buf[6];

  buf[0] = buf[1] = LOBOT_SERVO_FRAME_HEADER;
  buf[2] = id;
  buf[3] = 3;
  buf[4] = LOBOT_SERVO_ANGLE_LIMIT_READ;
  buf[5] = LobotCheckSum(buf);
  SerialX.write(buf, 6);
 
  while (SerialX.available())
    SerialX.read();

  while (!SerialX.available()) {
    count -= 1;
    if (count < 0)
      return -2048;
  }

  if (LobotSerialServoReceiveHandle(SerialX, buf) > 0)
    {
      retL = (int16_t)BYTE_TO_HW(buf[2], buf[1]);
      retH = (int16_t)BYTE_TO_HW(buf[4], buf[3]);
    }
  else
    ret = -2048;
  return ret;
}
//读取电压
int LobotSerialServoReadVin(HardwareSerial &SerialX, uint8_t id)
{
  int count = 10000;
  int ret;
  byte buf[6];

  buf[0] = buf[1] = LOBOT_SERVO_FRAME_HEADER;
  buf[2] = id;
  buf[3] = 3;
  buf[4] = LOBOT_SERVO_VIN_READ;
  buf[5] = LobotCheckSum(buf);
  SerialX.write(buf, 6);

  while (SerialX.available())
    SerialX.read();

  while (!SerialX.available()) {
    count -= 1;
    if (count < 0)
      return -2048;
  }

  if (LobotSerialServoReceiveHandle(SerialX, buf) > 0)
    ret = (int16_t)BYTE_TO_HW(buf[2], buf[1]);
  else
    ret = -2049;
    
  return ret;
}

//读取电压范围
int vinL;
int vinH;
int LobotSerialServoReadVinLimit(HardwareSerial &SerialX, uint8_t id)
{
  int count = 10000;
  int ret;
  byte buf[6];

  buf[0] = buf[1] = LOBOT_SERVO_FRAME_HEADER;
  buf[2] = id;
  buf[3] = 3;
  buf[4] = LOBOT_SERVO_VIN_LIMIT_READ;
  buf[5] = LobotCheckSum(buf);
  SerialX.write(buf, 6);
 
  while (SerialX.available())
    SerialX.read();

  while (!SerialX.available()) {
    count -= 1;
    if (count < 0)
      return -2048;
  }

  if (LobotSerialServoReceiveHandle(SerialX, buf) > 0)
    {
      vinL = (int16_t)BYTE_TO_HW(buf[2], buf[1]);
      vinH = (int16_t)BYTE_TO_HW(buf[4], buf[3]);
    }
  else
    ret = -2048;
  return ret;
}

//读取温度报警阈值
int LobotSerialServoReadTempLimit(HardwareSerial &SerialX, uint8_t id)
{
  int count = 10000;
  int ret;
  byte buf[6];

  buf[0] = buf[1] = LOBOT_SERVO_FRAME_HEADER;
  buf[2] = id;
  buf[3] = 3;
  buf[4] = LOBOT_SERVO_TEMP_MAX_LIMIT_READ;
  buf[5] = LobotCheckSum(buf);
  SerialX.write(buf, 6);

  while (SerialX.available())
    SerialX.read();

  while (!SerialX.available()) {
    count -= 1;
    if (count < 0)
      return -2048;
  }

  if (LobotSerialServoReceiveHandle(SerialX, buf) > 0)
    ret = (int16_t)BYTE_TO_HW(0x00, buf[1]);
  else
    ret = -2049;
    
  return ret;
}

//读取温度
int LobotSerialServoReadTemp(HardwareSerial &SerialX, uint8_t id)
{
  int count = 10000;
  int ret;
  byte buf[6];

  buf[0] = buf[1] = LOBOT_SERVO_FRAME_HEADER;
  buf[2] = id;
  buf[3] = 3;
  buf[4] = LOBOT_SERVO_TEMP_READ;
  buf[5] = LobotCheckSum(buf);
  SerialX.write(buf, 6);

  while (SerialX.available())
    SerialX.read();

  while (!SerialX.available()) {
    count -= 1;
    if (count < 0)
      return -2048;
  }

  if (LobotSerialServoReceiveHandle(SerialX, buf) > 0)
    ret = (int16_t)BYTE_TO_HW(0x00, buf[1]);
  else
    ret = -2049;
    
  return ret;
}

//读取舵机状态
int LobotSerialServoReadLoadOrUnload(HardwareSerial &SerialX, uint8_t id)
{
  int count = 10000;
  int ret;
  byte buf[6];

  buf[0] = buf[1] = LOBOT_SERVO_FRAME_HEADER;
  buf[2] = id;
  buf[3] = 3;
  buf[4] = LOBOT_SERVO_LOAD_OR_UNLOAD_READ;
  buf[5] = LobotCheckSum(buf);
  SerialX.write(buf, 6);

  while (SerialX.available())
    SerialX.read();

  while (!SerialX.available()) {
    count -= 1;
    if (count < 0)
      return -2048;
  }

  if (LobotSerialServoReceiveHandle(SerialX, buf) > 0)
    ret = (int16_t)BYTE_TO_HW(0x00, buf[1]);
  else
    ret = -2049;
    
  return ret;
}
//停止转动
void LobotSerialServoStopMove(HardwareSerial &SerialX, uint8_t id)
{
  byte buf[6];
  buf[0] = buf[1] = LOBOT_SERVO_FRAME_HEADER;
  buf[2] = id;
  buf[3] = 3;
  buf[4] = LOBOT_SERVO_MOVE_STOP;
  buf[5] = LobotCheckSum(buf);
  SerialX.write(buf, 6);
}
//设置舵机模式
void LobotSerialServoSetMode(HardwareSerial &SerialX, uint8_t id, uint8_t Mode, int16_t Speed)
{
  byte buf[10];

  buf[0] = buf[1] = LOBOT_SERVO_FRAME_HEADER;
  buf[2] = id;
  buf[3] = 7;
  buf[4] = LOBOT_SERVO_OR_MOTOR_MODE_WRITE;
  buf[5] = Mode;
  buf[6] = 0;
  buf[7] = GET_LOW_BYTE((uint16_t)Speed);
  buf[8] = GET_HIGH_BYTE((uint16_t)Speed);
  buf[9] = LobotCheckSum(buf);

  SerialX.write(buf, 10);
}

//舵机上电
void LobotSerialServoLoad(HardwareSerial &SerialX, uint8_t id)
{
  byte buf[7];
  buf[0] = buf[1] = LOBOT_SERVO_FRAME_HEADER;
  buf[2] = id;
  buf[3] = 4;
  buf[4] = LOBOT_SERVO_LOAD_OR_UNLOAD_WRITE;
  buf[5] = 1;
  buf[6] = LobotCheckSum(buf);
 
  SerialX.write(buf, 7);

}
//舵机掉电
void LobotSerialServoUnload(HardwareSerial &SerialX, uint8_t id)
{
  byte buf[7];
  buf[0] = buf[1] = LOBOT_SERVO_FRAME_HEADER;
  buf[2] = id;
  buf[3] = 4;
  buf[4] = LOBOT_SERVO_LOAD_OR_UNLOAD_WRITE;
  buf[5] = 0;
  buf[6] = LobotCheckSum(buf);
 
  SerialX.write(buf, 7);
}

include.h

Code:

#define GET_LOW_BYTE(A) (uint8_t)((A))
//宏函数 获得A的低八位
#define GET_HIGH_BYTE(A) (uint8_t)((A) >> 8)
//宏函数 获得A的高八位
#define BYTE_TO_HW(A, B) ((((uint16_t)(A)) << 8) | (uint8_t)(B))
//宏函数 以A为高八位 B为低八位 合并为16位整形

#define ID_ALL 254  //ID为254时，会向所有舵机进行广播，可用于读取未知ID的舵机信息

#define LOBOT_SERVO_FRAME_HEADER         0x55
#define LOBOT_SERVO_MOVE_TIME_WRITE      1
#define LOBOT_SERVO_MOVE_TIME_READ       2
#define LOBOT_SERVO_MOVE_TIME_WAIT_WRITE 7
#define LOBOT_SERVO_MOVE_TIME_WAIT_READ  8
#define LOBOT_SERVO_MOVE_START           11
#define LOBOT_SERVO_MOVE_STOP            12
#define LOBOT_SERVO_ID_WRITE             13
#define LOBOT_SERVO_ID_READ              14
#define LOBOT_SERVO_ANGLE_OFFSET_ADJUST  17
#define LOBOT_SERVO_ANGLE_OFFSET_WRITE   18
#define LOBOT_SERVO_ANGLE_OFFSET_READ    19
#define LOBOT_SERVO_ANGLE_LIMIT_WRITE    20
#define LOBOT_SERVO_ANGLE_LIMIT_READ     21
#define LOBOT_SERVO_VIN_LIMIT_WRITE      22
#define LOBOT_SERVO_VIN_LIMIT_READ       23
#define LOBOT_SERVO_TEMP_MAX_LIMIT_WRITE 24
#define LOBOT_SERVO_TEMP_MAX_LIMIT_READ  25
#define LOBOT_SERVO_TEMP_READ            26
#define LOBOT_SERVO_VIN_READ             27
#define LOBOT_SERVO_POS_READ             28
#define LOBOT_SERVO_OR_MOTOR_MODE_WRITE  29
#define LOBOT_SERVO_OR_MOTOR_MODE_READ   30
#define LOBOT_SERVO_LOAD_OR_UNLOAD_WRITE 31
#define LOBOT_SERVO_LOAD_OR_UNLOAD_READ  32
#define LOBOT_SERVO_LED_CTRL_WRITE       33
#define LOBOT_SERVO_LED_CTRL_READ        34
#define LOBOT_SERVO_LED_ERROR_WRITE      35
#define LOBOT_SERVO_LED_ERROR_READ       36

jmarsh · Jun 18, 2024

What voltage is the control board using? Unlike the Uno the Teensy can only handle 3.3v... You didn't mention anything about a common ground connection which might have actually saved it from being damaged.

Yucheng · Jun 18, 2024

jmarsh said:
What voltage is the control board using? Unlike the Uno the Teensy can only handle 3.3v... You didn't mention anything about a common ground connection which might have actually saved it from being damaged.

The control board also handles the power for the motor which is 11.1v. It also has 4 pins 5v, GND, RX, TX. I have connected 5v and GND to the teensy, and I am using RX1 and TX1 for TX and RX from the control board respectively

jmarsh · Jun 18, 2024

You don't want to do that. The voltage on the UART pins will be too much for the Teensy.

Yucheng · Jun 18, 2024

jmarsh said:
You don't want to do that. The voltage on the UART pins will be too much for the Teensy.

I am a bit confused. The diagram for teensy 4.1 suggests that there is a pin that can handle voltage from 3.6 to 5.5 volts

jmarsh · Jun 18, 2024

Yucheng said:
I am a bit confused. The diagram for teensy 4.1 suggests that there is a pin that can handle voltage from 3.6 to 5.5 volts

That would be the VIN pin only, because it feeds a power regulator. The I/O pins are only expected to take 3.3V (around 3.6V max). If you connect them to a 5V UART it will damage either those pins or the entire chip.

Yucheng · Jun 18, 2024

jmarsh said:
That would be the VIN pin only, because it feeds a power regulator. The I/O pins are only expected to take 3.3V (around 3.6V max). If you connect them to a 5V UART it will damage either those pins or the entire chip.

I see. But what is going on with the SerialX.available(). Why does it always return false? Do you have any ideas

Hardware serial

Yucheng

New member

jmarsh

Well-known member

Yucheng

New member

jmarsh

Well-known member

Yucheng

New member

jmarsh

Well-known member

Yucheng

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