Difference between revisions of "Spi lcd 1.3 protocol"
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(Created page with '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. Afte…') |
(No difference)
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Revision as of 11:53, 14 February 2012
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.
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.
port | function |
---|---|
0x00 | display data. |
0x01 | write data as command to LCD. |
0x10 | any data clears the screen. |
0x11 | move the cursor to x, y. y is the top 3 bits, x is the bottom 5 bits of the data. |
0x12 | set contrast. |
0x13 | set backlight. |
0xf0 | change address. |