Spi lcd 1.3 protocol

2013-05-16T12:48:44Z

Leelassen:

The addresses on the SPI bus are 7 bits wide. The lower bit specifies if the transaction is to be a read or a write. Write transactions have the lower bit cleared (0), read transactions have the lower bit set (1).

Each transaction on the SPI bus starts with the address of the board. The spi_lcd board will ignore any transactions on the SPI bus that do not start with its own address.

After the address a single byte indicates the "port" on the board that the data is written to. The software can thus define 256 ports on each board.

Also see the [[general SPI protocol]]

= write ports =

Some ports just set a single value. So writing more than one byte to such a port is redundant. Other ports are logically a stream of bytes. So writing more than one byte is encouraged.

The spi_lcd board defines several ports.
{| border=1
! port !! function
|-
| 0x00 || display data.
|-
| 0x01 || write data as command to LCD.
|-
| 0x08 || Set startup message line 1. After setting the startup message please wait 100ms before sending the next line.
|-
| 0x09 || Set startup message line 2.
|-
| 0x0a || Set startup message line 3.
|-
| 0x0b || Set startup message line 4.
|-
| 0x10 || any data clears the screen.
|-
| 0x11 || move the cursor to line l, position p. <br>l is the top 3 bits<br>p is the bottom 5 bits of the data.
|-
| 0x12 || set contrast.
|-
| 0x13 || set backlight.
|-
| 0x14 || reinit LCD.
|-
| 0xf0 || change address.
|}

= read ports =
The spi_lcd board supports two read ports:

{| border=1
! port !! function
|-
| 0x01 || identification string. (terminated with 0).
|-
| 0x02 || read eeprom (serial number).
|}
= examples =

== read identification ==

read the identification string of the board. ('spi_lcd 1.3').
{| border=1
! data sent !! data recieved || explanation
|-
| 0x83 || xx || select destination with address 0x82 for READ.
|-
| 0x01 || xx || identify
|-
| xx || 0x73 || 's'
|-
| xx || 0x70 || 'p'
|-
| xx || 0x69 || 'i'
|-
| xx || ... || etc.
|}

== Send text to display ==
Display the string "Hello World!" (only the first 5 bytes of the string shown).
{| border=1
! data sent !! data recieved || explanation
|-
| 0x82 || xx || select destination with address 0x82 for WRITE
|-
| 0x00 || xx || datastream
|-
| 0x48 || xx || 'H'
|-
| 0x65 || xx || 'e'
|-
| 0x6c || xx || 'l'
|-
| 0x6c || xx || 'l'
|-
| 0x6f || xx || 'o'
|-
| xx || ... || etc.
|}

== set cursor position ==
move to line 1, character 5:
{| border=1
! data sent !! data recieved || explanation
|-
| 0x82 || xx || select destination with address 0x82 for WRITE
|-
| 0x11 || xx || port 0x11 = set cursor position.
|-
| 0x25 || xx || 0x25 = 001 00101 = line 1 position 5.
|}

== define custom character ==

A usage of the 0x01 port is to define custom characters. Here in a less verbose format:
82 01 40 # set CGRAM char 0 line 0
82 00 01 02 04 08 10 10 10 # define character 0 (7 bytes)
82 11 00 # move to home position
82 00 41 42 0 # print characters A B and our newly defined character.

Use 0x48 instead of 0x40 to define character number "1" (Up to 8 characters can be defined in CGRAM).

the character data "01 02 04 08 10 10 10" is just an example. 11 11 11 1f 11 11 11 is the uppercase "H" that I have on my display right now.

the last two lines are just a example of how to get back to "display" mode. It works for me I don't have the inclination to find other ways.

Getting back to display mode (DDRAM) and moving to home position (address 0) can also be done by sending: "82 01 80"

== Showing a cursor/blinking cursor ==

Show cursor position:
82 01 0E # cursor on
82 01 0C # cursor off

Blinking (current position):
82 01 0D #blink on
82 01 0C #blink off

== scrolling the display ==

Send
82 01 18
to scroll the display one place left. Use 0x1c instead of 0x18 to scroll right. Replace 0x82 by the address of your display (e.g. 0x94 if you have an rpi_ui at the default address).

Spi lcd 1.3 protocol

2013-05-16T12:41:07Z

Leelassen: /* define custom character */

The addresses on the SPI bus are 7 bits wide. The lower bit specifies if the transaction is to be a read or a write. Write transactions have the lower bit cleared (0), read transactions have the lower bit set (1).

Each transaction on the SPI bus starts with the address of the board. The spi_lcd board will ignore any transactions on the SPI bus that do not start with its own address.

After the address a single byte indicates the "port" on the board that the data is written to. The software can thus define 256 ports on each board.

Also see the [[general SPI protocol]]

= write ports =

Some ports just set a single value. So writing more than one byte to such a port is redundant. Other ports are logically a stream of bytes. So writing more than one byte is encouraged.

The spi_lcd board defines several ports.
{| border=1
! port !! function
|-
| 0x00 || display data.
|-
| 0x01 || write data as command to LCD.
|-
| 0x08 || Set startup message line 1. After setting the startup message please wait 100ms before sending the next line.
|-
| 0x09 || Set startup message line 2.
|-
| 0x0a || Set startup message line 3.
|-
| 0x0b || Set startup message line 4.
|-
| 0x10 || any data clears the screen.
|-
| 0x11 || move the cursor to line l, position p. <br>l is the top 3 bits<br>p is the bottom 5 bits of the data.
|-
| 0x12 || set contrast.
|-
| 0x13 || set backlight.
|-
| 0x14 || reinit LCD.
|-
| 0xf0 || change address.
|}

= read ports =
The spi_lcd board supports two read ports:

{| border=1
! port !! function
|-
| 0x01 || identification string. (terminated with 0).
|-
| 0x02 || read eeprom (serial number).
|}
= examples =

== read identification ==

read the identification string of the board. ('spi_lcd 1.3').
{| border=1
! data sent !! data recieved || explanation
|-
| 0x83 || xx || select destination with address 0x82 for READ.
|-
| 0x01 || xx || identify
|-
| xx || 0x73 || 's'
|-
| xx || 0x70 || 'p'
|-
| xx || 0x69 || 'i'
|-
| xx || ... || etc.
|}

== Send text to display ==
Display the string "Hello World!" (only the first 5 bytes of the string shown).
{| border=1
! data sent !! data recieved || explanation
|-
| 0x82 || xx || select destination with address 0x82 for WRITE
|-
| 0x00 || xx || datastream
|-
| 0x48 || xx || 'H'
|-
| 0x65 || xx || 'e'
|-
| 0x6c || xx || 'l'
|-
| 0x6c || xx || 'l'
|-
| 0x6f || xx || 'o'
|-
| xx || ... || etc.
|}

== set cursor position ==
move to line 1, character 5:
{| border=1
! data sent !! data recieved || explanation
|-
| 0x82 || xx || select destination with address 0x82 for WRITE
|-
| 0x11 || xx || port 0x11 = set cursor position.
|-
| 0x25 || xx || 0x25 = 001 00101 = line 1 position 5.
|}

== define custom character ==

A usage of the 0x01 port is to define custom characters. Here in a less verbose format:
82 01 40 # set CGRAM char 0 line 0
82 00 01 02 04 08 10 10 10 # define character 0 (7 bytes)
82 11 00 # move to home position
82 00 41 42 0 # print characters A B and our newly defined character.

Use 0x48 instead of 0x40 to define character number "1" (Up to 8 characters can be defined in CGRAM).

the character data "01 02 04 08 10 10 10" is just an example. 11 11 11 1f 11 11 11 is the uppercase "H" that I have on my display right now.

the last two lines are just a example of how to get back to "display" mode. It works for me I don't have the inclination to find other ways.

Getting back to display mode (DDRAM) and moving to home position (address 0) can also be done by sending: "82 01 80"

== scrolling the display ==

Send
82 01 18
to scroll the display one place left. Use 0x1c instead of 0x18 to scroll right. Replace 0x82 by the address of your display (e.g. 0x94 if you have an rpi_ui at the default address).

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Spi lcd 1.3 protocol

Spi lcd 1.3 protocol