9 BIT spi

Thorsten · Guest

Hi,

does anyone know if it possible to send 9Bit over SPI at one time?
I have a nokia display which requires a 9Bit SPI mode.

Please help me :-)

Thanks

Thorsten

Humberto · Posted: Fri Apr 21, 2006 8:25 am

With SPI protocol it is possible only to send 8 bits at a time (1 byte), to send 9 bits you will need 2 frames.
As long as I know, all SPI protocol is arranged around 8 bit format.
Could you address us a link to see the Nokia spec regarding 9 bits ?

Humberto

Ttelmah · Guest

You just manually clock the data yourself.
It is a sort of 'half SPI' (single directional transfer only).
There have been some routines published here in the past, and a search oug to find them. There are two different controller chips used, and quite a few programming differences.

Best Wishes

Thorsten · Guest

Hi,

the chip is an Epson controller. The code exampels here i found already, but i want to modify them to use the hardware spi. The Epson controller requires a
9 Bit protocol. The first bit will say which type of data you send ( data or command ). Now it looks like it will not possible to use the hardware spi :-(

Humberto · Posted: Fri Apr 21, 2006 10:36 am

amcfall · Joined: 20 Oct 2005 Posts: 44

Mark · Joined: 07 Sep 2003 Posts: 2838 Location: Atlanta, GA

Read the datasheet again especially section 8.1.3. It says that data can be entered either 8 or 9 bit. For 8 bit, another pin is required to tell whether it is command or data.

You might be able to still use the hardware SPI with 9 bits. Keep the CS low and clock in 16 bits of data and then pulse the CS line. I believe that the chip will only look at the last 9 bits of data so the first byte would be either command or data (0 or 1) and the 2nd the actual 8 bits of data.[/quote]

amcfall · Joined: 20 Oct 2005 Posts: 44