我有一个可以在Maple Mini上运行的代码，但是我必须将硬件更改为Nucleo F030r8，因为它具有更多的ADC，并且完全糟透了。
在modbus_update()函数中，检查inputBuffer的大小，并且仅当此变量的值大于0时，以下代码才应运行。
if (inputBuffer > 0 && micros() - microsFlag >= T3_5) {
...
}
但是即使inputBuffer的值正好为0，它也可以运行。奇怪的是，此代码（具有不同的串行端口打开方法）可以在Maple Mini上完美运行。有谁知道可能是什么问题？
这是整个代码：
#define BAUDRATE 19200
#define RE_PIN PC12
#define TE_PIN PF4
#define LED_PIN LED_BUILTIN
#define SLAVE_ID 1
#define BUFFER_SIZE 256 // max frame size
#define READ_INTERNAL_REGISTERS 4 // function code
#define MIN_REGISTER_ADDRESS 30001
#define MAX_REGISTER_ADDRESS 30020
#define MAX_SENSORS_PER_ROW 10
#define SENSORS_PER_ROW 7
#define MAX_ROWS 2
#define ROWS 1
#define DEBUG true
#define INVALID_VALUE 0x7FFF
const byte INPUTS[] = {PA0, PA1, PA4, PB0, PC1, PC0};
unsigned char frame[BUFFER_SIZE];
unsigned char functionCode;
unsigned int T1;
unsigned int T1_5; // inter character time out
unsigned int T3_5; // frame delay
unsigned long millisFlag = 0;
unsigned long microsFlag = 0;
unsigned char inputBuffer = 0;
int dlyCounter = 0;
int16_t sensorVals[MAX_SENSORS_PER_ROW * MAX_ROWS];
/*
HardwareSerial *modbus = &Serial;
HardwareSerial Serial1(PA10, PA9);
HardwareSerial *debug = &Serial1;
*/
HardwareSerial debug(PA10, PA9);
void setup() {
pinMode(LED_PIN, OUTPUT);
for (int i = 0; i < SENSORS_PER_ROW; i++) {
pinMode(INPUTS[i], INPUT_PULLUP);
}
debug.begin(BAUDRATE, SERIAL_8E1);
modbus_configure(BAUDRATE, 0); // baud rate, low latency
microsFlag = micros();
}
void loop() {
readSensorVals(100);
modbus_update();
}
unsigned int modbus_update() {
unsigned char overflow = 0;
while (Serial.available()) {
if (overflow) {
Serial.read(); // empty the input buffer
} else {
if (inputBuffer == BUFFER_SIZE) {
overflow = 1;
} else {
frame[inputBuffer] = Serial.read();
inputBuffer++;
}
}
microsFlag = micros();
}
// If an overflow occurred return to the main sketch
// without responding to the request i.e. force a timeout
if (overflow) {
debug.println("Error: input buffer overflow");
return 0;
}
// if inter frame delay occurred, check the incoming package
if (inputBuffer > 0 && micros() - microsFlag >= T3_5) {
debug.println("\nIncoming frame:");
for (int i = 0; i < inputBuffer; i++) {
debug.print(frame[i], HEX);
debug.print(" ");
}
debug.println();
// check CRC
unsigned int crc = ((frame[inputBuffer - 2] << 8) | frame[inputBuffer - 1]); // combine the crc Low & High bytes
if (calculateCRC(frame, inputBuffer - 2) != crc) {
debug.println("Error: checksum failed");
inputBuffer = 0;
return 0;
}
debug.println("CRC OK");
// check ID
unsigned char id = frame[0];
if (id > 242) {
debug.println("Error: Invalid ID");
inputBuffer = 0;
return 0;
}
// check if it's a broadcast message
if (id == 0) {
debug.println("Broadcast message");
inputBuffer = 0;
return 0;
}
if (id != SLAVE_ID) {
debug.println("Not my ID");
inputBuffer = 0;
return 0;
}
debug.println("ID OK");
// check function code
functionCode = frame[1];
if (functionCode != READ_INTERNAL_REGISTERS) {
debug.println("Exception: illegal function");
exceptionResponse(1);
inputBuffer = 0;
return 0;
}
debug.println("Function code OK");
// check frame size (function 4 frame MUST be 8 bytes long)
if (inputBuffer != 8) {
// some workaround here:
//if (inputBuffer != 8 || !(inputBuffer == 9 && frame[inputBuffer] == 0)) {
debug.println("Error: inaccurate frame length");
inputBuffer = 0;
return 0;
}
debug.println("Frame size OK");
// check data address range
unsigned int noOfRegisters = ((frame[4] << 8) | frame[5]); // combine the number of register bytes
if (noOfRegisters > 125) {
debug.println("Exception: illegal data address");
exceptionResponse(2);
inputBuffer = 0;
return 0;
}
unsigned int firstRegAddress = ((frame[2] << 8) | frame[3]); // combine the starting address bytes
debug.print("First address: ");
debug.println(firstRegAddress);
unsigned int lastRegAddress = firstRegAddress + noOfRegisters - 1;
debug.print("Last address: ");
debug.println(lastRegAddress);
unsigned char noOfBytes = noOfRegisters * 2;
unsigned char responseFrameSize = 5 + noOfBytes; // ID, functionCode, noOfBytes, (dataLo + dataHi) * number of registers, crcLo, crcHi
unsigned char responseFrame[responseFrameSize];
responseFrame[0] = SLAVE_ID;
responseFrame[1] = 0x04;
responseFrame[2] = noOfBytes;
unsigned char address = 3; // PDU starts at the 4th byte
for (int index = (int)(firstRegAddress - MIN_REGISTER_ADDRESS); index <= (int)(lastRegAddress - MIN_REGISTER_ADDRESS); index++) {
int16_t temp = (index >= 0 && index < MAX_ROWS * MAX_SENSORS_PER_ROW) ? sensorVals[index] : INVALID_VALUE;
responseFrame[address] = temp >> 8; // split the register into 2 bytes
address++;
responseFrame[address] = temp & 0xFF;
address++;
}
unsigned int crc16 = calculateCRC(responseFrame, responseFrameSize - 2);
responseFrame[responseFrameSize - 2] = crc16 >> 8; // split crc into 2 bytes
responseFrame[responseFrameSize - 1] = crc16 & 0xFF;
debug.println("Frame to send:");
for (int i = 0; i < responseFrameSize; i++) {
debug.print(responseFrame[i], HEX);
debug.print(" ");
}
debug.println();
sendPacket(responseFrame, responseFrameSize);
inputBuffer = 0;
while (Serial.available()) { // empty input buffer
Serial.read();
}
}
}
void modbus_configure(long baud, unsigned char _lowLatency) {
Serial.begin(baud, SERIAL_8E1);
pinMode(TE_PIN, OUTPUT);
pinMode(RE_PIN, OUTPUT);
rxEnable(); // pin 0 & pin 1 are reserved for RX/TX. To disable set TE and RE pin < 2
if (baud == 1000000 && _lowLatency) {
T1 = 1;
T1_5 = 1;
T3_5 = 10;
} else if (baud >= 115200 && _lowLatency) {
T1 = 50;
T1_5 = 75;
T3_5 = 175;
} else if (baud > 19200) {
T1 = 500;
T1_5 = 750;
T3_5 = 1750;
} else {
T1 = 10000000 / baud;
T1_5 = 15000000 / baud; // 1T * 1.5 = T1.5
T3_5 = 35000000 / baud; // 1T * 3.5 = T3.5
}
}
void exceptionResponse(unsigned char exception) {
unsigned char responseFrameSize = 5;
unsigned char responseFrame[responseFrameSize];
responseFrame[0] = SLAVE_ID;
responseFrame[1] = (functionCode | 0x80); // set the MSB bit high, informs the master of an exception
responseFrame[2] = exception;
unsigned int crc16 = calculateCRC(responseFrame, 3); // ID, functionCode + 0x80, exception code == 3 bytes
responseFrame[3] = crc16 >> 8;
responseFrame[4] = crc16 & 0xFF;
sendPacket(responseFrame, responseFrameSize); // exception response is always 5 bytes (ID, functionCode + 0x80, exception code, 2 bytes crc)
}
unsigned int calculateCRC(unsigned char f[], byte bufferSize) {
unsigned int temp, temp2, flag;
temp = 0xFFFF;
for (unsigned char i = 0; i < bufferSize; i++) {
temp = temp ^ f[i];
for (unsigned char j = 1; j <= 8; j++) {
flag = temp & 0x0001;
temp >>= 1;
if (flag)
temp ^= 0xA001;
}
}
// Reverse byte order.
temp2 = temp >> 8;
temp = (temp << 8) | temp2;
temp &= 0xFFFF;
return temp; // the returned value is already swapped - crcLo byte is first & crcHi byte is last
}
void rxEnable() {
if (TE_PIN > 1 && RE_PIN > 1) {
digitalWrite(TE_PIN, LOW);
digitalWrite(RE_PIN, LOW);
digitalWrite(LED_PIN, LOW);
}
}
void txEnable() {
if (TE_PIN > 1 && RE_PIN > 1) {
digitalWrite(TE_PIN, HIGH);
digitalWrite(RE_PIN, HIGH);
digitalWrite(LED_PIN, HIGH);
}
}
void sendPacket(unsigned char f[], unsigned char bufferSize) {
txEnable();
delayMicroseconds(T3_5);
for (unsigned char i = 0; i < bufferSize; i++) {
Serial.write(f[i]);
}
Serial.flush();
delayMicroseconds(T3_5); // allow frame delay to indicate end of transmission
rxEnable();
}
// @param dly delay between sensor readings in milliseconds
void readSensorVals(int dly) {
if (millis() != millisFlag) {
dlyCounter++;
millisFlag = millis();
}
if (dlyCounter >= dly) { // read sensor values
for (int i = 0; i < MAX_ROWS; i++) {
for (int j = 0; j < MAX_SENSORS_PER_ROW; j++) {
int actualIndex = i * MAX_SENSORS_PER_ROW + j;
if (i < ROWS && j < SENSORS_PER_ROW) {
sensorVals[actualIndex] = random(20, 30);
//sensorVals[actualIndex] = (4096 - analogRead(INPUTS[j])) / 20 - 133;
} else {
sensorVals[actualIndex] = INVALID_VALUE;
}
}
}
dlyCounter = 0;
}
}