Initialing MFRC522 RFID chip in UART interface

Question

I'm using this arduino library to initial & communicate with my MFRC522 chip,library initially used SPI interface for communicating between MCU & RC522.When I'm using it in the SPI interface every thing is OK & correctly operate. Now I'm trying to change interface to the UART mode. Based on the MFRC522 datasheet from NXP,I setted pin status for UART mode. Also reading & writing sequences & UART framing address are based on datasheet. Also when I read VersionReg register of RC522 it successfully returned me 0x92 which mean it is V 2.0 but it can't detect presence of RFID tags. Is there any other differences between SPI & UART interface or any extra setting I must do? Has any one experiences with using this chip in UART mode?

My changes in register read & write functions:

unsigned char ReadRawRC(unsigned char Address)
{
     unsigned char ucAddr;
     unsigned char ucResult=0;

     ucAddr = Address | 0x80;

     UART_SendBlocking(USART0, &ucAddr, 1);
     UART_ReadBlocking(USART0, &ucResult, 1);

     return ucResult;
}

/////////////////////////////////////////////////////////////////////
//@ Function: write RC522 register
//@ Parameter Description: Address [IN]: register address
//Value [IN]: write value
/////////////////////////////////////////////////////////////////////
void WriteRawRC(unsigned char Address, unsigned char value)
{
        unsigned char ucAddr;
        unsigned char ucValu;

        ucAddr = Address & 0x7F;
        ucValu = value;
        UART_SendBlocking(USART0, &ucAddr, 1);
        UART_SendBlocking(USART0, &ucValu, 1);

}

score 2 · Accepted Answer · answered Jul 18 '16 at 10:46

The problem was about differences in address byte in UART mode and SPI mode, as you can see in this picture new modified read /write functions act very well:

unsigned char ucAddr;
unsigned char ucValu;
uint8_t IncomingData;

    /////////////////////////////////////////////////////////////////////
    //@ Function: Reading RC522 register
    //@ Parameter Description: Address [IN]: register address
    //@ Return: The value read
    /////////////////////////////////////////////////////////////////////
    unsigned char ReadRawRC(unsigned char Address)
    {

         ucAddr = Address | 0x80;

             dataSign=false;
         Chip_UART_SendBlocking(LPC_USART0, &ucAddr, 1);
             StopWatch_DelayMs(3);

             if(dataSign==true)
             return IncomingData;

             return 0;
    }

    /////////////////////////////////////////////////////////////////////
    //@ Function: write RC522 register
    //@ Parameter Description: Address [IN]: register address
    //Value [IN]: write value
    /////////////////////////////////////////////////////////////////////
    void WriteRawRC(unsigned char Address, unsigned char value)
    {
            ucAddr = Address & 0x7F;
            ucValu = value;
        Chip_UART_SendBlocking(LPC_USART0, &ucAddr, 1);
        Chip_UART_SendBlocking(LPC_USART0, &value, 1);
    }

Initialing MFRC522 RFID chip in UART interface

1 Answers1