I got a new toy! an Mopho analog synth from Dave Smith Instruments. First use.. a companion to my MIDI lavalamp to free it up from PC based soft synths. Since my original MIDI lavalamp project was based on a standard Arduino, I decided this time to make a quick little module for it using a PIC16F688 (my current weapon of choice)
Here is the circuit on stripboard
...the mess on the back...
...and the schematic...
... the lamp is wired up as described on this post
... and the PIC source code is included below (SourceBoost compiler)
#include <system.h>
#include <memory.h>
#define ANA_0 0b00000000
#define ANA_1 0b00000100
#define ANA_2 0b00001000
#define ANA_3 0b00001100
#define ANA_4 0b00010000
#define ANA_5 0b00010100
#define ANA_6 0b00011000
#define ANA_7 0b00011100
#define ADC_MAX 6
#define P_HEARTBEAT porta.5
#pragma DATA _CONFIG, _MCLRE_OFF&_WDT_OFF&_INTRC_OSC_NOCLKOUT
#pragma CLOCK_FREQ 8000000
#define ADC_AQUISITION_DELAY 10
typedef unsigned char byte;
enum {
ADC_CONNECT,
ADC_ACQUIRE,
ADC_CONVERT
};
void init_usart()
{
pir1.1 = 1; //TXIF transmit enable
pie1.1 = 0; //TXIE no interrupts
baudctl.4 = 0; // synchronous bit polarity
baudctl.3 = 1; // enable 16 bit brg
baudctl.1 = 0; // wake up enable off
baudctl.0 = 0; // disable auto baud detect
txsta.6 = 0; // 8 bit transmission
txsta.5 = 1; // transmit enable
txsta.4 = 0; // async mode
txsta.2 = 0; // high baudrate BRGH
rcsta.7 = 1; // serial port enable
rcsta.6 = 0; // 8 bit operation
rcsta.4 = 0; // enable receiver
spbrgh = 0; // brg high byte
spbrg = 15; // brg low byte (31250)
}
void send(unsigned char c)
{
txreg = c;
while(!txsta.1);
}
void sendController(byte channel, byte controller, byte value)
{
P_HEARTBEAT = 1;
send(0xb0 | channel);
send(controller&0x7f);
send(value&0x7f);
P_HEARTBEAT = 0;
}
byte adcInput[ADC_MAX] = {ANA_2, ANA_3, ANA_4, ANA_5, ANA_6, ANA_7};
byte adcInitComplete = 0;
int adcResult[ADC_MAX] = {-1,-1,-1,-1,-1,-1};
int adcIndex = 0;
int adcState = ADC_CONNECT;
////////////////////////////////////////////////////////////////
//
// doADC
//
// State machine for running the ADC and updating the adcResult
// array with the result from each analog input
//
void doADC()
{
switch(adcState)
{
// Connect ADC to the correct analog input
case ADC_CONNECT:
adcon0=0b10000001 | adcInput[adcIndex];
tmr0 = 0;
adcState = ADC_ACQUIRE;
// fall through
// Waiting for a delay while the ADC input settles
case ADC_ACQUIRE:
if(tmr0 > ADC_AQUISITION_DELAY)
{
// Start the conversion
adcon0.1=1;
adcState = ADC_CONVERT;
}
break;
// Waiting for the conversion to complete
case ADC_CONVERT:
if(!adcon0.1)
{
// store the result
adcResult[adcIndex] = (((int)adresh)<<8)|adresl;
// and prepare for the next ADC
if(++adcIndex>=ADC_MAX)
{
adcIndex = 0;
adcInitComplete = 1;
}
adcState = ADC_CONNECT;
}
break;
}
}
#define BUFLEN 8
typedef struct
{
char midiChannel;
char midiController;
int minADC;
int maxADC;
char currentValue;
char history[BUFLEN];
} CONTROLLER;
CONTROLLER controllers[ADC_MAX] = {0};
void initInput(int which, byte channel, byte controller)
{
controllers[which].midiChannel = channel;
controllers[which].midiController = controller;
controllers[which].minADC = -1;
controllers[which].maxADC = -1;
controllers[which].currentValue = -1;
}
void checkInput(int which)
{
// pointer to the controllers
CONTROLLER *p = &controllers[which];
// read the raw analog value 0-1023
int adc = adcResult[which];
// remember highest and lowest values
if((p->minADC == -1) || (p->minADC > adc))
p->minADC = adc;
if((p->maxADC == -1) || (p->maxADC < adc))
p->maxADC = adc;
// get the range of known readings
int range = p->maxADC - p->minADC;
if(range < 1)
range = 1;
// scale the current value into the range
// NB no floating point support...
int newValue = (127*(adc - p->minADC))/range;
// add the value into the history buffer
long smoothed = 0;
for(int j=0; j<BUFLEN-1;++j)
{
p->history[j] = p->history[j+1];
smoothed += p->history[j];
}
p->history[BUFLEN-1] = newValue;
smoothed += newValue;
smoothed /= BUFLEN;
// has the value changed?
if(smoothed != p->currentValue)
{
sendController(p->midiChannel, p->midiController, smoothed);
p->currentValue= smoothed;
}
}
void main()
{
int i;
// osc control / 8MHz / internal
osccon = 0b01110001;
// timer0... configure source and prescaler
option_reg = 0b10000011;
cmcon0 = 7;
// configure io
trisa = 0b00001010;
trisc = 0b00001111;
ansel = 0b11111100;
// turn on the ADC
adcon1=0b00100000; //fOSC/32
adcon0=0b10000001; // Right justify / Vdd / AD on
// initialise MIDI comms
init_usart();
// Initialise the controllers
initInput(0, 0, 1);
initInput(1, 0, 2);
initInput(2, 0, 4);
initInput(3, 0, 7);
initInput(4, 0, 11);
initInput(5, 0, 74);
adcInitComplete = 0;
for(;;)
{
doADC();
if(adcInitComplete)
{
for(i=0;i<ADC_MAX;++i)
checkInput(i);
adcInitComplete = 0;
delay_ms(20);
}
}
}
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