[sdiy] DIY PG-800?

[Colin f]

> -----Original Message-----
> From: synth-diy-bounces at dropmix.xs4all.nl 
> [mailto:synth-diy-bounces at dropmix.xs4all.nl] On Behalf Of 
> Matthew Smith
> Sent: 24 December 2008 22:43
> To: synth-diy at dropmix.xs4all.nl
> Subject: Re: [sdiy] DIY PG-800?

> Colin's page provides all the codes bar the one for the 
> 'write' command.

Write is E1.

> To complete the picture so that the system could be 
> reproduced without 
> the firmware I would need to know details of the serial protocol that 
> are not documented in the service notes:
> 
> * Should data be presented on the rising or falling edge of the clock?

It should be presented on the rising edge.
It's read by the JX after the falling edge.

> * Is the data 7 or 8 bit?

It's 8 bits, as implied by the use of bit 7 to indicate a command byte.
Transmission is MSB first.

> * What polarity is the data (is the logic inverted?)

No inversion.

> * What part does the 'ready out' line play?

The ready line is asserted by the PG when it has data to send to the JX.
It clears ready after the data has been read.

Cheers,
Colin f