SPI with adxl345

RE: SPI with adxl345

rushin — Sun, 13 Mar 2016 15:10:20 GMT

hey. sorry i can't understand this .

  m_tx_data_spi = (0x80|address)|0x40;

here if i put address 0x2D then m_tx_data_spi = 0xED. can you explain more??

RE: SPI with adxl345

bjorn-spockeli — Mon, 25 Jan 2016 14:43:07 GMT

(0x80|address) sets the Read/Write bit ( Bit 7 ) and if you are reading more than register(i.e. more than 1 byte ) you have to OR (0x80|address) with 0x40 to set the Multiple-byte bit ( Bit 6 ). The first byte looks like this:

   (MSB) | Read/Write (1bit) | Multiple-Byte( 1bit ) | Register Adress (6 bits) | (LSB)

RE: SPI with adxl345

rushin — Mon, 25 Jan 2016 14:37:32 GMT

why addres is ored with 0x80 and 0x40??

RE: SPI with adxl345

bjorn-spockeli — Mon, 25 Jan 2016 14:31:40 GMT

If you are reading to more than one register you have to set the Multiple-Byte bit in the first byte transfer.

RE: SPI with adxl345

rushin — Mon, 25 Jan 2016 14:19:12 GMT

but explain me why we are doing this??

  if(bytes > 1)
    {
        m_tx_data_spi = (0x80|address)|0x40;
    }
    else
    {
        m_tx_data_spi = 0x80|address;
    }

RE: SPI with adxl345

rushin — Mon, 25 Jan 2016 14:18:35 GMT

hi thanks for its working

RE: SPI with adxl345

bjorn-spockeli — Mon, 25 Jan 2016 09:41:38 GMT

Take a look at the SPI driver I made for the ADXL375.

Driver Files:

main.c

ADXL375_SPI.c

ADXL375_SPI.h

-Bjørn