question about the spi of am335x

Hi,

Yes, this is possible, but you will need to write your own SW to support this display.

There is the AM335X Technical Reference Manual, Rev. L, which can be downloaded from the AM335X product page. Section 24 describes the McSPI peripheral.

hi Biser,
thanks for your reply, in the AM335X Technical Reference Manual,24.3.2.12 3- or 4-Pin Mode, there give a figure of 3-pin mode, if i use 4-pin mode, how to connect the 4 pin(SPICLK, SOMI, SIMO, and CS) to the LCD(the interface description see the picture below), is there anything i need to take care?

Best Regards
Jun

SPICLK - clock from AM335X to LCD

SOMI - data from LCD to AM335X

SIMO - data from AM335X to LCD

CS - chip select signal from AM335X to LCD

i also saw the am335x technical reference manual, in chapter 24.3.2.12, there are only 3 pin model block diagram,  less information on 4-pin SPI between AM335X and LCD. as you replied that 4 pin SPI can be used between AM335X and LCD, so,

1   should i set MCSPI_MODULCTRL[PIN34] to 0, right?  

2  should i pull down or pull up resistors in the 4 pin line or not?

many thanks.  

Jun,

Please post the entire LCD interface connector (or LCD datasheet, not the chip datasheet you posted earlier). I would like to see all the signals needed for this LCD.

Biser,
here is the LCD datasheet:TDO-QVGA0160A90020-V1(1.60D)v1.0.pdf

SDA has been set as a output pin of data, WR has been set as a input pin of data

Nothing is attached. You can simply drag and drop it in the reply window.

I'm afraid I don't understand how this can be connected to the AM335X McSPI. I suggest you ask the LCD manufacturer for recommended connections to standard SPI interface.

You can connect SPI_CS in three-pin mode too. See Figure 24-4 in the AM335X TRM Rev. L for reference (CS is called SPIEN in this figure). About the pullup/pulldown resistors you can use the internal pullup/pulldowns, which can be configured individually for each pin in the pad control register (TRM section 9.2.2).

much appreciate for your prompt answer on pullup/pulldown resistors,  clear, 

Regarding 3-pin SPI bus, as i see Figure 24-4, it seems AM335X do as master and LCD do as slaver? so the SPIDAT is only SPI data out?  SPIDAT can not be I/O both?   correct me if i am wrong.  thanks.

ming peng said:

SPIDAT can not be I/O both?

This is not correct. Direction can be changed by SPIDATDIR1 and SPIDATDIR0 bits in MCSPI_SYST register.

I have tried to reconfigure the spi1 pin direction via MCSPI_SYST (SPIDATDIR1 and SPIDATDIR0) it seems not to have any effect on where the data is shifted out. What am I missing? Can someone provide a code that does it?