SynthModules

Here's some data for the PSIM FAQ.

1:
I've spent some time with a MIDI analyzer looking at the data
on power up. The PSIM would almost always send one erroneous
byte on power up. I have found that this is caused by setting
the MIDI-out pin to an output. Instead I initialize it to an
input which eliminates the erroneous data from being sent.

The hserial commands initialize the pin so it functions properly.

;initialize pins
dirs=%0011111010000000 ;configure pin direction (1=output, 0=input)
;inputs:
;  midi-in, aux, speakjet flow control,
;  start, stop, in-4, in-3, in-2, in-1
;outputs:
;  load_dacs, ser_data, clock, stop led,
;  run led, speakjet serial output 
;  note: setting midi-out pin sends erroneous data

2:
The hserial commands initialize a 128 byte input buffer and a
128 byte output buffer that operate via interrupts.  The following
commands initialize the serial system.

;enable MIDI serial hardware
enablehserial
sethserial h31200,h8databits,hnoparity,h1stopbits

The following commands transfer midi_data to and from the buffers:

;send data to MIDI output buffer
hserout [midi_data]

;receive data from MIDI input buffer
;data_flg set 1 for data and 0 for no data
let data_flg=0 ;set empty flag
hserin 0,no_data,[midi_data]
if midi_data=$fe then no_data ;ignore active status
let data_flg=1 ;set data returned flag
no_data: