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TI launchpad SSI v SPI

HuskyEngineer
Prodigy 100 points

I'm completely new to using SPI devices and I'm trying to interface an SPI LCD device with the LM4F launchpad and I'm not sure where to look.

I found the ssi example in the Stellarisware files for IAR workbench but I've read online that SSI and SPI are not necessarily the same. I just want to make sure I can connect them in the following way:

uController   LCD
SSI0Clk      SCL (Serial Clock)
SSI0TX        SI (Serial Data)
SSI0FSS     CS (chip select)

There's also a pin on the LCD, A0 (Select registers 0: instruction , 1: data register) that I'm not sure where to connect to. I know SPI should have 4 lines but since the LCD is only input, I'd imagine there's no need to return anything to the uC.

This is the LCD I'm using: http://www.newhavendisplay.com/specs/NHD-C12832A1Z-NSW-BBW-3V3.pdf

I'd appreciate any help you can give!

  • 0
    Guru 117855 points

    Here - my best 2 minute effort as, Happy Hour calls...

    3 sigs you've listed look good - know that SSI0_TX also goes by MOSI. (master out slave in)  MCU outputs data to Slave's data input.

    You may (likely will) encounter trouble by using SSI0FSS.  You must "overlay" the LCDs data timing/signal chart against those w/in SSI section of the MCU manual - and choose the "best match."  Look especially @ the "clock edges" (you must match the LCDs requirements w/that of the MCU in one of the MCU's SSI modes)

    SSI0FSS may be best handled by not configuring that MCU pin as an SSI one.  Instead - configure it as GPIO Output - and "bit bang" it as specified by the Lcd data. 

    That extra A0 signal must be supplied by another GPIO - again configured as output.  Suggest that you set/clear that A0 pin prior to initiating the SSI sequence.  (although the Lcd's CS signal may have to be attended first)

    Should get you close - take your time w/both Lcd & Mcu manuals - things will become clearer...