Conflict when using UART and I2C in Arduino UNO

[vandat07]

Hello all,

I am using Arduino UNO, ESP8266 and PZEM-004T to measure electricity parameters and send to server via Wifi. The communication protocols are use as below:

PZEM-004T <=== UART(pin 10, pin 11) ===> UNO <=== I2C (pin A4, A5) ===> ESP8266 (Master)

UNO will read the parameters from PZEM-004T via UART, then send to ESP8266 via I2C.

When I use only UART or only I2C, everything works well. But when both are implemented in UNO, there will be a conflict, data read from PZEM-004T is correct but data received by ESP8266 is not correct.

I don't know how to overcome this issue. I have tried to modify the library to skip UART reading when I2C is ongoing (I2C_Flag = true). However, I could only read Voltage, Current, Power, and could not for Energy.

PZEM004T.h

#ifndef PZEM004T_H
#define PZEM004T_H

#if defined(ARDUINO) && ARDUINO >= 100
#include "Arduino.h"
#else
#include "WProgram.h"
#endif

// #define PZEM004_NO_SWSERIAL

#if (not defined(PZEM004_NO_SWSERIAL)) && (defined(__AVR__) || defined(ESP8266))
#define PZEM004_SOFTSERIAL
#endif

#if defined(PZEM004_SOFTSERIAL)
#include <SoftwareSerial.h>
#endif

#include <IPAddress.h>

#define PZEM_DEFAULT_READ_TIMEOUT 1000
#define PZEM_ERROR_VALUE -1.0

struct PZEMCommand {
    uint8_t command;
    uint8_t addr[4];
    uint8_t data;
    uint8_t crc;
};

class PZEM004T
{
public:
    PZEM004T(uint8_t receivePin, uint8_t transmitPin);
    PZEM004T(HardwareSerial *port);
    ~PZEM004T();

    void setReadTimeout(unsigned long msec);
    unsigned long readTimeout() {return _readTimeOut;}

    float voltage(const IPAddress &addr, **bool I2C_Flag**);
    float current(const IPAddress &addr, **bool I2C_Flag**);
    float power(const IPAddress &addr, **bool I2C_Flag**);
    float energy(const IPAddress &addr, **bool I2C_Flag**);

    bool setAddress(const IPAddress &newAddr);
    bool setPowerAlarm(const IPAddress &addr, uint8_t threshold);

private:
    Stream *serial;

    bool _isSoft;
    unsigned long _readTimeOut = PZEM_DEFAULT_READ_TIMEOUT;

    void send(const IPAddress &addr, uint8_t cmd, **bool I2C_Flag = false**, uint8_t data = 0); 
    bool recieve(uint8_t resp, **bool I2C_Flag = false**, uint8_t *data = 0);

    uint8_t crc(uint8_t *data, uint8_t sz);
};

#endif // PZEM004T_H

PZEM004T.cpp

#include "PZEM004T.h"

#define PZEM_VOLTAGE (uint8_t)0xB0
#define RESP_VOLTAGE (uint8_t)0xA0

#define PZEM_CURRENT (uint8_t)0xB1
#define RESP_CURRENT (uint8_t)0xA1

#define PZEM_POWER   (uint8_t)0xB2
#define RESP_POWER   (uint8_t)0xA2

#define PZEM_ENERGY  (uint8_t)0xB3
#define RESP_ENERGY  (uint8_t)0xA3

#define PZEM_SET_ADDRESS (uint8_t)0xB4
#define RESP_SET_ADDRESS (uint8_t)0xA4

#define PZEM_POWER_ALARM (uint8_t)0xB5
#define RESP_POWER_ALARM (uint8_t)0xA5

#define RESPONSE_SIZE sizeof(PZEMCommand)
#define RESPONSE_DATA_SIZE RESPONSE_SIZE - 2

#define PZEM_BAUD_RATE 9600

#ifdef PZEM004_SOFTSERIAL    
PZEM004T::PZEM004T(uint8_t receivePin, uint8_t transmitPin)
{
    SoftwareSerial *port = new SoftwareSerial(receivePin, transmitPin);
    port->begin(PZEM_BAUD_RATE);
    this->serial = port;
    this->_isSoft = true;
}
#endif

PZEM004T::PZEM004T(HardwareSerial *port)
{
    port->begin(PZEM_BAUD_RATE);
    this->serial = port;
    this->_isSoft = false;
}

PZEM004T::~PZEM004T()
{
    if(_isSoft)
        delete this->serial;
}

void PZEM004T::setReadTimeout(unsigned long msec)
{
    _readTimeOut = msec;
}

float PZEM004T::voltage(const IPAddress &addr, **bool I2C_Flag**)
{

    uint8_t data[RESPONSE_DATA_SIZE];

    send(addr, PZEM_VOLTAGE, **I2C_Flag**);
    if(!recieve(RESP_VOLTAGE, **I2C_Flag**, data))
        return PZEM_ERROR_VALUE;

    return (data[0] << 8) + data[1] + (data[2] / 10.0);

}

float PZEM004T::current(const IPAddress &addr, **bool I2C_Flag**)
{   

    uint8_t data[RESPONSE_DATA_SIZE];

    send(addr, PZEM_CURRENT, **I2C_Flag**);
    if(!recieve(RESP_CURRENT, **I2C_Flag**, data))
        return PZEM_ERROR_VALUE;

    return (data[0] << 8) + data[1] + (data[2] / 100.0);

}

float PZEM004T::power(const IPAddress &addr, **bool I2C_Flag**)
{

    uint8_t data[RESPONSE_DATA_SIZE];

    send(addr, PZEM_POWER, **I2C_Flag**);
    if(!recieve(RESP_POWER, **I2C_Flag**, data))
        return PZEM_ERROR_VALUE;

    return (data[0] << 8) + data[1];

}

float PZEM004T::energy(const IPAddress &addr, **bool I2C_Flag**)
{

    uint8_t data[RESPONSE_DATA_SIZE];

    send(addr, PZEM_ENERGY, **I2C_Flag**);
    if(!recieve(RESP_ENERGY, **I2C_Flag**, data))
        return PZEM_ERROR_VALUE;

    return ((uint32_t)data[0] << 16) + ((uint16_t)data[1] << 8) + data[2];

}

bool PZEM004T::setAddress(const IPAddress &newAddr)
{
    send(newAddr, PZEM_SET_ADDRESS);
    return recieve(RESP_SET_ADDRESS);
}
/*
bool PZEM004T::setPowerAlarm(const IPAddress &addr, uint8_t threshold)
{
    send(addr, PZEM_POWER_ALARM, threshold);
    return recieve(RESP_POWER_ALARM);
}

*/

void PZEM004T::send(const IPAddress &addr, uint8_t cmd, bool I2C_Flag, uint8_t data)    
{
    PZEMCommand pzem;

    pzem.command = cmd;
    for(int i=0; i<sizeof(pzem.addr); i++)
        pzem.addr[i] = addr[i];
    pzem.data = data;

    uint8_t *bytes = (uint8_t*)&pzem;
    pzem.crc = crc(bytes, sizeof(pzem) - 1);

    while(serial->available()){
        **if (I2C_Flag) return;**
        serial->read();
    }

    serial->write(bytes, sizeof(pzem));
}

bool PZEM004T::recieve(uint8_t resp, bool I2C_Flag, uint8_t *data)
{
    uint8_t buffer[RESPONSE_SIZE];

#ifdef PZEM004_SOFTSERIAL    
    if(_isSoft)
        ((SoftwareSerial *)serial)->listen();
#endif

    unsigned long startTime = millis();
    uint8_t len = 0;
    while((len < RESPONSE_SIZE) && (millis() - startTime < _readTimeOut))
    {   **if (I2C_Flag) return false;** 

        if(serial->available() > 0)
        {
            uint8_t c = (uint8_t)serial->read();
            if(!c && !len)
                continue; // skip 0 at startup
            buffer[len++] = c;          
        }
        yield();    // do background netw tasks while blocked for IO (prevents ESP watchdog trigger)
    }   

    if(len != RESPONSE_SIZE)
        return false;

    if(buffer[6] != crc(buffer, len - 1))
        return false;

    if(buffer[0] != resp)
        return false;

    if(data)
    {       
        for(int i=0; i<RESPONSE_DATA_SIZE; i++){
            data[i] = buffer[1 + i];    
        }

    }

    return true;
}

uint8_t PZEM004T::crc(uint8_t *data, uint8_t sz)
{
    uint16_t crc = 0;
    for(uint8_t i=0; i<sz; i++)
        crc += *data++;
    return (uint8_t)(crc & 0xFF);
}

Please let me know if you have any solutions for this! Thanks a lot!