SPI to 632


New member
Just got my 632 serial LCD, and trying to connect it
to the SPI port of my 8051 microcontroller. And really
stuck in it now.

For my microcontroller, it is Analog Device product,
ADuC812, it has own SPI port. And pins for SPI are
MISO(master in), MOSI(master out), SCLOCK, and
SS(slave selection). And I connect MOSI to DATAIN in
632, and SCLOCK to SPI_CLK. and when I write to SFR
register SPIDAT in microcontroller, which will send
byte to SPI port, I can not get any dispaly, just some
flashing cursor.

First, the LCD is ok, I used wintest to test it, and
it is perfect. And for my program, if I simulate it on
my computer, it is also ok, I can see the message from
SPI windows. But when I connect from my
microcontroller board to LCD, nothing happened. Must be some settings in the program and the connection problem. I am
fresh new for this kind of stuff, and really need your
any device. Any connection suggestion or some sample
code? Your help is really appreciated.

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CF Tech

Some things to check:

1) JPA must be closed for the 632 to be in SPI mode (this will how up on the boot screen).

2) JPE must be closed if DATA_IN is swinging from 0v to 5v

3) SPI_CS must go low before a the SPI transfer, and ideally will go high between each byte to guarantee bit synchronization.

4) The SPI on the 632 & 634 is slow by SPI standards (though it is still faster than RS-232). Make sure your SPI_CLK frequency is 18KHz or lower.

5) In almost all cases, SPI_BUSY will stay low. If you experience trouble and it is going high, you will need to wait for it to go low before senging the next byte.

Be sure to look at the "SPI Timing Diagram" of the data sheet.