{"id":3182,"date":"2025-01-21T14:36:49","date_gmt":"2025-01-21T14:36:49","guid":{"rendered":"https:\/\/iotthinghub.com\/?p=3182"},"modified":"2025-01-21T15:48:09","modified_gmt":"2025-01-21T15:48:09","slug":"stm32-spi-conference-entry-using-rfid-card","status":"publish","type":"post","link":"https:\/\/iotthinghub.com\/?p=3182","title":{"rendered":"STM32 SPI: Conference Entry using RFID Card"},"content":{"rendered":"\n

Some time we need a square door lock or square entry for security reasons. RFID card has a unique ID with 1Kb ram. We can write or read from the memory block. The MFRC522 is a highly integrated reader\/writer IC for contactless communication at 13.56MHz. Since on board we have 27.12MHz frequency, we have to divide the clock. The MFRC522 can operate in SPI, I2<\/sup>C or UART protocol. In this article we will develop a conference entry with RFID card. In this tutorial we use ST microcontroller with its internal RTC (Real Time Clock) function. You can introduce GSM technology for soft remainder since it has internal calendar with alarm feature. To know more about RFID card reader please goes through my RFID Card Interference section. In Atmel section we learn about SPI communication, the same function works on STM32. Here some useful HAL library for SPI interface as follow-<\/p>\n\n\n

\nHAL_SPI_Transmit\/ HAL_SPI_Transmit_IT\/ HAL_SPI_Transmit_DMA (SPI_HandleTypeDef *hspi, uint8_t *pData, uint16_t Size, uint32_t Timeout);\nHAL_SPI_Receive\/ HAL_SPI_Receive_IT \/ HAL_SPI_Receive_DMA (SPI_HandleTypeDef *hspi, uint8_t *pData, uint16_t Size, uint32_t Timeout);\nHAL_SPI_TransmitReceive\/ HAL_SPI_TransmitReceive_IT \/ HAL_SPI_TransmitReceive_DMA (SPI_HandleTypeDef *hspi, uint8_t *pTxData, uint8_t *pRxData, uint16_t Size, uint32_t Timeout);\n<\/pre><\/div>\n\n\n
if we use IT no Timeout parameter is needed.<\/p>\n\n\n\n
It has also Interrupt function like i.e. HAL_SPI_TxCpltCallback(&hspi), HAL_SPI_RxCpltCallback(&hspi) etc.<\/p>\n\n\n\n
In my ATmel section we learn the basic interfacing with RFID. Let\u2019s start your journey with the basic of RFID interface, before start first goes through the datasheet of MFRC522 IC. For SPI communication the 7th<\/sup> bit represent read\/write & 0th<\/sup> bit is always 0. So whenever we want to read keep the 7th<\/sup> bit 1, reaming 6 bit will be the address of the register and 0th<\/sup> bit will 0. Similarly for writing purpose, changes in the 7th<\/sup> bit only. The MFRC522 card reader has 7bit unique address to operate as follow-<\/p>\n\n\n\n
\"\"<\/figure>\n\n\n\n
Let\u2019s build our read & write function using STM32F103RCT6 IC with spi2 & GPIOA pin 4 for chip selection<\/p>\n\n\n
\n#define CS_SELECT                 HAL_GPIO_WritePin(GPIOA,GPIO_PIN_4,GPIO_PIN_RESET)\n#define CS_DESELECT               HAL_GPIO_WritePin(GPIOA,GPIO_PIN_4,GPIO_PIN_SET)\n<\/pre><\/div>\n\n\n
\n
\nuint8_t readFromRegister(uint8_t addr) \n{\n  uint8_t value[2]={((addr<<1)&0x7E)|0x80,0};\n  uint8_t Rx_buffer[2];\n  CS_SELECT;\n  \/\/Read Address format: 1XXXXXX0\n  HAL_SPI_TransmitReceive(&hspi2,value,Rx_buffer,2,100);\n  CS_DESELECT;\n  return Rx_buffer[1];\n}\n<\/pre><\/div><\/div>\n\n\n\n
\nvoid writeToRegister(uint8_t addr, uint8_t val) \n{\n  CS_SELECT;\n  uint8_t value[2]={(addr<<1)&0x7E,val};\n  uint8_t Rx_buffer[2];\n  \/\/Write Address format: 0XXXXXX0\n  HAL_SPI_TransmitReceive(&hspi2,value,Rx_buffer,2,100);\n  CS_DESELECT;\n}\n<\/pre><\/div><\/div>\n<\/div>\n\n\n\n
For example to reset the MFRC522 we have to send command 0x0F to register Command register: 0x01<\/p>\n\n\n
\nvoid reset(void) \n{\n  writeToRegister(CommandReg, MFRC522_SOFTRESET); \/\/ MFRC522_SOFTRESET: 0x0F\n}  \n<\/pre><\/div>\n\n\n
To know all the register please goes though the datasheet of MFRC522. Let\u2019s make another 2 function to set & clear the bit of a register.<\/p>\n\n\n\n
\n
\nvoid setBitMask(uint8_t addr, uint8_t mask) \n{\n  uint8_t current;\n  current = readFromRegister(addr);\n  writeToRegister(addr, current | mask);\n}\n<\/pre><\/div><\/div>\n\n\n\n
\nvoid clearBitMask(uint8_t addr, uint8_t mask) \n{\n  uint8_t current;\n  current = readFromRegister(addr);\n  writeToRegister(addr, current & (~mask));\n}\n<\/pre><\/div><\/div>\n<\/div>\n\n\n\n
Some of our basic functions are done to communicate with MFRC522 card reader. Now our first step is to initialize the MFRC522 card reader. Let\u2019s initialize the MFRC522 with 24ms timer, 100% ASK, CRC value 0x6363 & turn on antenna.<\/p>\n\n\n
\nvoid begin(void) \n{\n  HAL_GPIO_WritePin(GPIOC,GPIO_PIN_4,GPIO_PIN_SET);\n  reset();\n  \/\/Timer: TPrescaler*TreloadVal\/6.78MHz = 24ms\n  writeToRegister(TModeReg, 0x8D);   \/\/ Tauto=1; f(Timer) = 6.78MHz\/TPreScaler\n  writeToRegister(TPrescalerReg, 0x3E);  \/\/ TModeReg[3..0] + TPrescalerReg\n  writeToRegister(TReloadRegL, 30);  writeToRegister(TReloadRegH, 0);\n  writeToRegister(TxAutoReg, 0x40);      \/\/ 100%ASK\n  writeToRegister(ModeReg, 0x3D);        \/\/ CRC initial value 0x6363\n  setBitMask(TxControlReg, 0x03);        \/\/ Turn antenna on.\n}\n<\/pre><\/div>\n\n\n
For reference use https:\/\/github.com\/Hamid-R-Tanhaei\/RFID-MIFARE-RC522-ARM-STM32<\/a>. When we place a RF card it will return 64bits of data pattern. We just use first 4bits, since the first 4bits are the unique address of the RFID Card. We can also read & write some data to the RF ID card since it has 1kb memory. Let\u2019s start our project with some RFID card reading & note the resultant value to a public name. You can use OLED for display the card number. Here I use debug feature & also I2<\/sup>C OLED for data readout.<\/p>\n\n\n
\nuint8_t FoundTag,ReadTag,TagData[16]; \/\/ Variable used to store Full Tag Data\nFoundTag = requestTag(MF1_REQIDL, TagData); \nif (FoundTag == 0x00) ReadTag = antiCollision(TagData);\nsprintf(display_tag," %2X,%2X,%2X,%2X ",TagData[0],TagData[1],TagData[2],TagData[3]);\nOLCD_write_string(6,0,display_tag);\n<\/pre><\/div>\n\n\n
Here TagData returns 4bits unique address. Assign some name to store the data i.e.<\/p>\n\n\n\n
    \n
  • 0xB3: 0x4A: 0x63: 0xA9 \u2013 Subeer Sarkar -> name1<\/li>\n\n\n\n
  • 0x13: 0xF9: 0xFF: 0xFA \u2013 Swarnolata\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 ->\u00a0 name2<\/li>\n<\/ul>\n\n\n\n
    Above is the reading data of 2 RFID card. Using those card we just use condition statement to turn ON\/OFF a GPIO pin, here I used GPIOA -> Pin8. The basic code as follow-<\/p>\n\n\n
    \nuint8_t Card1[4]={0xB3,0x4A,0x63,0xA9}; \/\/ Subeer Sarkar\nuint8_t Card2[4]={0x13,0xF9,0xFF,0xFA}; \/\/ Swarnolata\nHAL_RTC_GetTime(&hrtc,&sTime,RTC_FORMAT_BCD);\nHAL_RTC_GetDate(&hrtc,&sDate,RTC_FORMAT_BCD);\nsprintf(display_time," %02X:%02X:%02X ",sTime.Hours,sTime.Minutes,sTime.Seconds);\nOLCD_write_string(3,0,display_time);\nsprintf(display_time," %02X\/%02X\/%02X %s",sDate.Date,sDate.Month,sDate.Year,day_name[sDate.WeekDay+1]);\n\t  OLCD_write_string(4,0,display_time);\nif((Card1[0]==TagData[0])&&(Card1[1]==TagData[1])&&(Card1[2]==TagData[2])&&(Card1[3]==TagData[3]))\n\t {\n\t\t OLCD_write_string(5,0,"Subeer Sarkar");            \/\/ person name here\n         OLCD_write_string(6,0,display_time);\n\t\t HAL_GPIO_WritePin(GPIOA, GPIO_PIN_8, GPIO_PIN_RESET);  \/\/ open for 10s\n\t\t HAL_Delay(10000);\n\t\t HAL_GPIO_WritePin(GPIOA, GPIO_PIN_8, GPIO_PIN_SET);\n\t\t OLCD_write_string(5,0,"               ");\n         OLCD_write_string(6,0,"               ");\n\t     }\nelse if((Card2[0]==TagData[0])&&(Card2[1]==TagData[1])&&(Card2[2]==TagData[2])&&(Card2[3]==TagData[3]))\n     {\n\t\t OLCD_write_string(5,0,"Swarnolata   ");            \/\/ person name here\n         OLCD_write_string(6,0,display_time);\n\t\t HAL_GPIO_WritePin(GPIOA, GPIO_PIN_8, GPIO_PIN_RESET);  \/\/ open for 10s\n\t\t HAL_Delay(10000);\n\t\t HAL_GPIO_WritePin(GPIOA, GPIO_PIN_8, GPIO_PIN_SET);\n\t\t OLCD_write_string(5,0,"               ");\n         OLCD_write_string(6,0,"               ");\n\t }\n<\/pre><\/div>\n\n\n
    You can introduce as many cards as you wanted & add more else if loop. Here I use internal RTC clock. For most squared entry you can introduce GSM SMS system to send the date & time to the selected person for conference. Assume the conference time 6th<\/sup> January 2025 at 10am to 11am & the control logic works according to that time and card only works on that interval,\u00a0 the logic will be \u2013<\/p>\n\n\n
    \nFoundTag = requestTag(MF1_REQIDL, TagData); \nif(sTime.Hours == 0x10 && sDate.Date == 0x06 &&  sDate.Month == 0x01)\nif (FoundTag == 0x00) ReadTag = antiCollision(TagData); \/\/ Read tag only at 10am, 06\/01\/25\n<\/pre><\/div>\n\n\n
    \n