At Sat, 21 Sep 2019 05:46:56 -0700 (PDT) [email protected] wrote:
> > > > I am using ST7735S.It has a 3 wire serial mode which is 9 bit in every > "byte transaction, 9th bit 1 for command and 0 for data. Oh, so instead of the D/C control line, it gets a 9th serial bit... > It does have a 4 wire configuration (which would have made my life much > easier), but the hardware vendor wanted it to be 3 wire mode. Can we even Yes, the 4 wire configuration greatly simplifies things -- you would be able to just snag the Adafruit driver and replace the low-level SPI I/O to use the Linux ioctls. What is the reasoning for wanting a 3 wire over a 4 wire? Is there a shortage of GPIO lines (eg the GPIO lines are all committed to something else). > do this over SPIDEV in user space? I have set 9 bit word size and nothing > seems to help. Well, /usr/include/spi/spidev.h on my Raspberry Pi actually talks about sending 9-bit messages in its comments... So, I am *presuming* that it is possible... > > On Saturday, September 21, 2019 at 8:13:00 AM UTC-4, Robert Heller wrote: > > > > At Sat, 21 Sep 2019 04:34:24 -0700 (PDT) [email protected] > > <javascript:> wrote: > > > > > > > > > > > > > > > > > > > > I have SPi0 and SPI enabled in device tree. I looped back shorting MISO > > and > > > MOSI and Can receive the send messages provided its all 8 bit word > > length > > > > > > The issue is I am trying to talk to St7735S display driver over SPI ,it > > > needs 9 bit command and data transfer. > > > > Are you sure about that? > > > > The Adafruit Arduino St7735S driver library seems to use 8-bit data and > > commands and is doing 8-bit SPI transfers. And I know that works, because > > I am > > using it with both an Adafruit Feather M0 express and an Adafruit Metro > > Mini > > project (both programed via the Arduino IDE, but the driver code could be > > ported to Linux easily enough). > > > > > > > > So I am trying to send > > tx1[6]={0x01AA,0x0177,0x0188,0x0100,0x01FF,0x0166}; > > > , defined as short int (2 bytes) . but when I receive response its > > > > > > 01AA 5577 and so on. its not correct and nothing happens on display? Any > > > help > > > > > > > -- > > Robert Heller -- 978-544-6933 > > Deepwoods Software -- Custom Software Services > > http://www.deepsoft.com/ -- Linux Administration Services > > [email protected] <javascript:> -- Webhosting Services > > > > > -- Robert Heller -- 978-544-6933 Deepwoods Software -- Custom Software Services http://www.deepsoft.com/ -- Linux Administration Services [email protected] -- Webhosting Services -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/beagleboard/20190921144408.0FE7A26C07FC%40sharky3.deepsoft.com.
