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LMH6518: SPI configuration basics

Part Number: LMH6518

Hi,

I am trying to interface an xmega32D4 with the LMH6518 SPI.

The SDIO pin of the DVGA is a bidirectional pin while the xmega is using independent pins for data input and output.

So i am thinking whether i should use the HW spi peripheral or do it by software.

First of all the schematic in the DS has confused me a bit.

1) During read ops, the DVGA is fed with the clock pulses, starting at the assertion of the CS, of the microcontroller only while the command transmission pulses last (SCLK 1-8).

2) Then the SCLK of the DVGA is the clock source and the microcontroller, from now on, must be configured as a slave in order for the SCLK of the microcontroller to be an input (SCLK 9-25).

3) During write ops, the DVGA is fed with the clock pulses, starting at the assertion of the CS, of the microcontroller throughout the entire 24-pulses sequence (SCLK 1-25).

4) The arrows, in the image below, showing upwards give me the impression that CLK data is sourced by the DVGA towards the microcontroller which would be wrong based on 1, 2 & 3. Do the arrows showing upwards indicate CLK data flowing from the microcontroller towards the DVGA?

Regards

Manos Tsachalidis

  • Hello Manos,

    The SCLK signals are all sourced by the micro-controller. The arrows indicate a rising or falling edge for the SCLK signal. 

    In regards to using the micro-controller with the bidirectional pin of the LMH6518, you can use the configuration shown below:

    Best,

    Hasan Babiker