STM32 Reading Example

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uint8_t IS4310_I2C_Chip_Address; // This variable stores the I2C chip address of the IS4310.
IS4310_I2C_Chip_Address = 0x11; // The IS4310's I2C address is 0x11.
// The STM32 HAL I2C library requires the I2C address to be shifted left by one bit.
// Let's shift the IS4310 I2C address accordingly:
IS4310_I2C_Chip_Address = IS4310_I2C_Chip_Address << 1;

uint16_t Holding_Register_Address_To_Read; // This variable stores the holding register address we want to read from the IS4310.
Holding_Register_Address_To_Read = 500; // We will read address 0, which contains the Modbus Slave ID.

// The following array will store the read data.
// Since each holding register is 16 bits long, reading one register requires reading 2 bytes.
uint8_t readResultArray[2];


/*
 * This is the HAL function to read from an I2C memory device. The IS4310 is designed to operate as an I2C memory.
 *
 * Parameters:
 * 1. &hi2c1: This is the name of the I2C that you're using. You set this in the CubeMX. Don't forget the '&'.
 * 2. IS4310_I2C_Chip_Address: The I2C address of the IS4310 (must be left-shifted).
 * 3. Holding_Register_Address_To_Read: The holding register address to read from the IS4310.
 * 4. I2C_MEMADD_SIZE_16BIT: You must indicate the memory addressing size. The IS4310 memory addressing is 16-bits.
 *  This keyword is an internal constant of HAL libraries.
 * 5. readResultArray: An 8-bit array where the HAL stores the read data.
 * 6. 2: The number of bytes to read. Since one holding register is 16 bits, we need to read 2 bytes.
 * 7. 1000: Timeout in milliseconds. If the HAL fails to read within this time, it will skip the operation
 *    to prevent the code from getting stuck.
 */
HAL_I2C_Mem_Read(&hi2c1, IS4310_I2C_Chip_Address, Holding_Register_Address_To_Read, I2C_MEMADD_SIZE_16BIT, readResultArray, 2, 1000);

/*
 * At this point, we have the Modbus Slave ID stored in the readResultArray.
 * The upper 8 bits of the holding register are stored in readResultArray[0],
 * and the lower 8 bits are stored in readResultArray[1].
 *
 * By default, the Modbus Slave ID is 1, so:
 * - readResultArray[0] will contain 0.
 * - readResultArray[1] will contain 1.
 *
 * Storing the result across two variables isn't ideal, so let's combine them into a single 16-bit variable:
 */
uint16_t readResult;
readResult = readResultArray[0];
readResult = readResult << 8;
readResult = readResult | readResultArray[1];

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Last updated 2 months ago

uint8_t IS4310_I2C_Chip_Address; // This variable stores the I2C chip address of the IS4310. IS4310_I2C_Chip_Address = 0x11; // The IS4310's I2C address is 0x11. // The STM32 HAL I2C library requires the I2C address to be shifted left by one bit. // Let's shift the IS4310 I2C address accordingly: IS4310_I2C_Chip_Address = IS4310_I2C_Chip_Address << 1; uint16_t Holding_Register_Address_To_Read; // This variable stores the holding register address we want to read from the IS4310. Holding_Register_Address_To_Read = 500; // We will read address 0, which contains the Modbus Slave ID. // The following array will store the read data. // Since each holding register is 16 bits long, reading one register requires reading 2 bytes. uint8_t readResultArray[2]; /* * This is the HAL function to read from an I2C memory device. The IS4310 is designed to operate as an I2C memory. * * Parameters: * 1. &hi2c1: This is the name of the I2C that you're using. You set this in the CubeMX. Don't forget the '&'. * 2. IS4310_I2C_Chip_Address: The I2C address of the IS4310 (must be left-shifted). * 3. Holding_Register_Address_To_Read: The holding register address to read from the IS4310. * 4. I2C_MEMADD_SIZE_16BIT: You must indicate the memory addressing size. The IS4310 memory addressing is 16-bits. * This keyword is an internal constant of HAL libraries. * 5. readResultArray: An 8-bit array where the HAL stores the read data. * 6. 2: The number of bytes to read. Since one holding register is 16 bits, we need to read 2 bytes. * 7. 1000: Timeout in milliseconds. If the HAL fails to read within this time, it will skip the operation * to prevent the code from getting stuck. */ HAL_I2C_Mem_Read(&hi2c1, IS4310_I2C_Chip_Address, Holding_Register_Address_To_Read, I2C_MEMADD_SIZE_16BIT, readResultArray, 2, 1000); /* * At this point, we have the Modbus Slave ID stored in the readResultArray. * The upper 8 bits of the holding register are stored in readResultArray[0], * and the lower 8 bits are stored in readResultArray[1]. * * By default, the Modbus Slave ID is 1, so: * - readResultArray[0] will contain 0. * - readResultArray[1] will contain 1. * * Storing the result across two variables isn't ideal, so let's combine them into a single 16-bit variable: */ uint16_t readResult; readResult = readResultArray[0]; readResult = readResult << 8; readResult = readResult | readResultArray[1];