.gitignore : Initial commit.

.gitignore

@@ -0,0 +1,4 @@
+*.elf
+*.hex
+*.pyc
+_autosave*

README.md

@@ -1,5 +1,7 @@
 This is the main repository for the CML picadae hardware
 and a control files.
 
+![Picadae](picadae_solenoids_closeup_20191012_2.jpg)
+
 - [__kicad__](kicad/README.md) contains the keyboard and pedal schematics and printed circuit board layout.
 - [__control__](control/README.md) contains the keyboard solenoid ATtiny85 firware, controller Arduino firmware and, Python control API and program.

control/app/picadae_api.py

@@ -17,7 +17,8 @@ class TinyOp(Enum):
     writeOp      = 5
     writeTableOp = 6
     holdDelayOp  = 7
-    invalidOp    = 8
+    flagsOp      = 8
+    invalidOp    = 9
     
 
 class TinyRegAddr(Enum):
@@ -40,7 +41,22 @@ class TinyRegAddr(Enum):
     kMaxAllowTmrAddr = 16
     kDelayCoarseAddr = 17
     kDelayFineAddr   = 18
+    kFlagsAddr       = 19
+    
+class TinyRegAddr0(Enum):
+    kRdRegAddrAddr   =  0
+    kRdSrcAddr       =  1
+    kWrRegAddrAddr   =  2
+    kWrDstAddr       =  3
+    kAttkDutyAddr    =  4
+    kAttkDurHiAddr   =  5
+    kAttkDurLoAddr   =  6
+    kDecayStepAddr   =  7
+    kDecayDecrAddr   =  8
+    kPwmDutyAddr     =  9
+    kErrorCodeAddr   = 10
 
+    
 class TinyConst(Enum):
     kRdRegSrcId    = TinyRegAddr.kRdRegAddrAddr.value    # 0
     kRdTableSrcId  = TinyRegAddr.kRdTableAddrAddr.value  # 1
@@ -263,6 +279,14 @@ class Picadae:
         
         return res
         
+    def set_flags( self, midi_pitch, flags ):
+        return  self.call_op( midi_pitch, TinyOp.flagsOp.value, [int(flags)] )
+        #return  self.call_op( midi_pitch, 5, [int(flags)] )
+
+    def get_flags( self, midi_pitch, time_out_ms=250 ):        
+         return self.block_on_picadae_read_reg( midi_pitch, TinyRegAddr.kFlagsAddr.value, byteOutN=1, time_out_ms=time_out_ms )
+         #return self.block_on_picadae_read_reg( midi_pitch, TinyRegAddr.kAttkDutyAddr.value, byteOutN=1, time_out_ms=time_out_ms )
+     
     
     def set_velocity_map( self, midi_pitch, midi_vel, pulse_usec ):
         coarse,fine = self._usec_to_coarse_and_fine( pulse_usec )
@@ -321,7 +345,18 @@ class Picadae:
             self.make_note( midi_pitch, base_atk_us + i*delta_us, dur_ms )
             time.sleep( dur_ms / 1000.0 )
         return Result()
+    
+    def make_scale( self, pitch0, pitch1, atk_us, dur_ms ):
 
+        if pitch0>pitch1:
+            printf("pitch0 must be <= pitch1")
+        else:
+            for pitch in range(pitch0,pitch1+1):            
+                self.make_note( pitch, atk_us, dur_ms )
+                time.sleep( dur_ms / 1000.0 )
+            return Result()
+            
+    
     def set_log_level( self, log_level ):
         self.log_level = log_level
         return Result()
@@ -344,6 +379,17 @@ class Picadae:
 
         x = coarse*coarse_usec + fine*self.prescaler_usec
         
+
+
+        ##### 
+        # n = int(16e6*usec/(256*1e6))
+
+        # coarse = n >> 8;
+        # fine   = n & 0xff;
+
+        # x = usec
+        ####
+
         print("C:%i F:%i : %i %i (%i)" % (coarse,fine, x, usec, usec-x ))
 
         return coarse,fine

control/app/picadae_shell.py

@@ -27,9 +27,12 @@ class PicadaeShell:
             'f':{ "func":"get_pwm_freq",   "minN":1,  "maxN":1, "help":"pwm freq <pitch>"},
             'I':{ "func":"set_pwm_div",    "minN":2,  "maxN":2, "help":"pwm div <pitch> <div> div:2=2,3=4,4=8,(5)=16 1us,6=32,7=64,8=128,9=256,10=512 32us, 11=1024,12=2048,13=4096,14=8192,15=16384"},
             'i':{ "func":"get_pwm_div",    "minN":1,  "maxN":1, "help":"pwm div <pitch>"},
+            'A':{ "func":"set_flags",      "minN":2,  "maxN":2, "help":"set flags <pitch> <flags>"},
+            'a':{ "func":"get_flags",      "minN":1,  "maxN":1, "help":"get flags <pitch>"},
             'W':{ "func":"write_table",    "minN":1,  "maxN":1, "help":"write_table <pitch>"},
             'N':{ "func":"make_note",      "minN":3,  "maxN":3, "help":"note <pitch> <atkUs> <durMs>"},
-            'S':{ "func":"make_seq",       "minN":5,  "maxN":5, "help":"seq  <pitch> <atkUs> <durMs> <deltaUs> <note_count>"}, 
+            'S':{ "func":"make_seq",       "minN":5,  "maxN":5, "help":"seq  <pitch> <atkUs> <durMs> <deltaUs> <note_count>"},
+            'C':{ "func":"make_scale",     "minN":4,  "maxN":4, "help":"scale <pitch0> <pitch1> <atkUs> <durMs>"},
             'L':{ "func":"set_log_level",  "minN":1,  "maxN":1, "help":"log <level> (0-1)."}
             }
 

control/tiny/Makefile

@@ -7,7 +7,7 @@ TTY=/dev/ttyACM0
 endif
 
 ifndef TARGET
-TARGET=i2c_timer_pwm
+TARGET=i2c_timer_pwm_2
 endif
 
 MCU=attiny85

control/tiny/i2c_timer_pwm_2.c

@@ -0,0 +1,685 @@
+//| Copyright: (C) 2018-2020 Kevin Larke <contact AT larke DOT org>
+//| License: GNU GPL version 3.0 or above. See the accompanying LICENSE file.
+
+// w 60 0  1 10    : w i2c_addr SetPWM enable duty_val
+// w 60 5 12  8 32 : w i2c_addr write addrFl|src coarse_val
+// w 60 4  0  5    : w i2c_addr read  src read_addr  (set the read address to register 5)
+// r 60 4  3       : r i2c_addr <dum> cnt            (read the first 3 reg's beginning w/ 5)
+/*                                    
+                                    AT TINY 85
+                                     +--\/--+
+                              RESET _| 1  8 |_ +5V
+             ~OC1B       HOLD PINB3 _| 2  7 |_ SCL         yellow 
+              OC1B      ONSET PINB4 _| 3  6 |_ PINB1 LED
+                                GND _| 4  5 |_ SDA         orange
+                                     +------+
+        * = Serial and/or programming pins on Arduino as ISP
+*/
+
+
+// This program acts as the device (slave) for the control program i2c/a2a/c_ctl
+#define F_CPU 16000000L
+
+#include <stdio.h>
+#include <avr/io.h>
+#include <util/delay.h>
+#include <avr/interrupt.h>
+
+#include "usiTwiSlave.h"
+
+#define HOLD_DIR DDB3
+#define ATTK_DIR DDB4
+#define LED_DIR  DDB1
+
+#define HOLD_PIN PINB3
+#define ATTK_PIN PINB4
+#define LED_PIN  PINB1
+
+// Opcodes
+enum
+{ 
+ kSetPwm_Op         =  0,  // Set PWM duty/hz/div   0 {<duty> {<freq> {<div>}}}  div:2=2,3=4,4=8,5=16,6=32,7=64,8=128,9=256,10=512,11=1024,12=2048,13=4096,14=8192,15=16384
+ kNoteOnVel_Op      =  1,  // Turn on note          3 {<vel>}
+ kNoteOnUsec_Op     =  2,  // Turn on note          4 {<coarse> {<fine> {<prescale>}}}
+ kNoteOff_Op        =  3,  // Turn off note         5
+ kSetReadAddr_Op    =  4,  // Set a read addr.      6 {<src>} {<addr>} }  src: 0=reg 1=table 2=eeprom
+ kWrite_Op          =  5,  // Set write             7 {<addrfl|src> {addr}  {<value0> ... {<valueN>}}  addrFl:0x80  src: 4=reg 5=table 6=eeprom
+ kWriteTable_Op     =  6,  // Write table to EEprom 9
+ kHoldDelay_Op      =  7,  // Set hold delay          {<coarse> {<fine>}}
+ kFlags_Op          =  8,  // Set flags variable 
+ kInvalid_Op        =  9   //                                             
+};
+
+
+enum
+{
+ kReg_Rd_Addr_idx    =  0,  // Next Reg Address to read
+ kTable_Rd_Addr_idx  =  1,  // Next Table Address to read
+ kEE_Rd_Addr_idx     =  2,  // Next EEPROM address to read
+ kRead_Src_idx       =  3,  // kReg_Rd_Addr_idx=reg,  kTable_Rd_Addr_idx=table, kEE_Rd_Addr_idx=eeprom
+ 
+ kReg_Wr_Addr_idx    =  4,  // Next Reg Address to write
+ kTable_Wr_Addr_idx  =  5,  // Next Table Address to write
+ kEE_Wr_Addr_idx     =  6,  // Next EEPROM address to write
+ kWrite_Dst_idx      =  7,  // kReg_Wr_Addr_idx=reg,  kTable_Wr_Addr_idx=table, kEE_Wr_Addr_idx=eeprom
+ 
+ kTmr_Coarse_idx     =  8,  //  
+ kTmr_Fine_idx       =  9,  // 
+ kTmr_Prescale_idx   = 10,  // Timer 0 clock divider: 1=1,2=8,3=64,4=256,5=1024  Default: 4 (16us)
+ 
+ kPwm_Duty_idx       = 11,  // 
+ kPwm_Freq_idx       = 12,  //
+ kPwm_Div_idx        = 13,  //
+
+ kState_idx          = 14, // 1=attk 2=hold
+ kError_Code_idx     = 15, // Error Code
+ kMax_Coarse_Tmr_idx = 16, // Max. allowable coarse timer value
+
+ kDelay_Coarse_idx   = 17, // (17,18)=2000 (0,6)=100
+ kDelay_Fine_idx     = 18,
+
+ kFlags_idx          = 19,
+ 
+ kMax_idx
+};
+
+enum
+{
+ kState_Attk_Fl        = 1,
+ kState_Hold_Fl        = 2
+};
+
+// ctl_regs[kFlags_idx]  bits
+enum
+{
+  kHoldOnAttk_Fl = 0x01
+};
+
+volatile uint8_t ctl_regs[] =
+{
+   0,                //  0 (0-(kMax_idx-1)) Reg Read Addr   
+   0,                //  1 (0-255)          Table Read Addr
+   0,                //  2 (0-255)          EE Read Addr  
+   kReg_Rd_Addr_idx, //  3 (0-2)    Read source
+   
+   0,                //  4 (0-(kMax_idx-1)) Reg Write Addr   
+   0,                //  5 (0-255)          Table Write Addr
+   0,                //  6 (0-255)          EE Write Addr
+   kReg_Wr_Addr_idx, //  7 (0-2)    Write source
+   
+   5,                //  8 (0-255)  Timer 0 Coarse Value (20400 us)
+   0,                //  9 (0-255)  Timer 0 Fine Value
+   4,                // 10 (1-5)    4=16us per tick
+   
+ 127,                // 11 (0-255)  Pwm Duty cycle
+ 255,                // 12 (0-255)  Pwm Frequency  (123 Hz)
+   5,                // 13 (0-15)   Pwm clock div 
+   
+   0,                // 14 state flags 1=attk   2=hold  (read/only)
+   0,                // 15 (0-255)  Error bit field
+   14,               // 16 (0-255) Max allowable coarse timer count
+
+   0,                // 17 (0-255) Hold coarse delay  
+ 250,                // 18 (0-255) Hold fine delay    0,6=100us 0,124=2000us w/ 16us Tmr0 tick
+   0                 // 19 (0-255) Flags 1=hold-on-attack
+   
+};
+
+// These registers are saved to Eeprom
+uint8_t eeprom_addr[] =
+{
+ kTmr_Prescale_idx,
+ kPwm_Duty_idx,
+ kPwm_Freq_idx,
+ kPwm_Div_idx
+};
+
+
+
+#define tableN 256
+uint8_t table[ tableN ]; // [ coarse_0,fine_0, coarse_1, fine_1, .... coarse_127,fine_127]
+ 
+
+enum
+{
+ kInvalid_Read_Src_ErrFl   = 0x01,
+ kInvalid_Write_Dst_ErrFl  = 0x02,
+ kInvalid_Coarse_Tmr_ErrFl = 0x04
+};
+
+#define set_error( flag ) ctl_regs[ kError_Code_idx ] |= (flag)
+
+//------------------------------------------------------------------------------
+//------------------------------------------------------------------------------
+//------------------------------------------------------------------------------
+//
+// EEPROM
+//
+
+void EEPROM_write(uint8_t ucAddress, uint8_t ucData)
+{
+  // Wait for completion of previous write 
+  while(EECR & (1<<EEPE))
+  {}
+    
+  EECR = (0<<EEPM1)|(0<<EEPM0); // Set Programming mode   
+  EEAR = ucAddress;             // Set up address and data registers 
+  EEDR = ucData;  
+  EECR |= (1<<EEMPE);           // Write logical one to EEMPE 
+  EECR |= (1<<EEPE);            // Start eeprom write by setting EEPE 
+}
+
+uint8_t EEPROM_read(uint8_t ucAddress)
+{
+  // Wait for completion of previous write 
+  while(EECR & (1<<EEPE))
+  {}
+    
+  EEAR = ucAddress;  // Set up address register 
+  EECR |= (1<<EERE); // Start eeprom read by writing EERE 
+  return EEDR;       // Return data from data register 
+}
+
+void write_table()
+{
+  uint8_t i;
+  uint8_t regN = sizeof(eeprom_addr);
+
+  // write the persistent registers
+  for(i=0; i<regN; ++i)
+    EEPROM_write( i, ctl_regs[ eeprom_addr[i] ] );
+
+  // write the table
+  for(i=0; i<tableN; ++i)
+    EEPROM_write( regN+i, table[i] );
+}
+
+void load_table()
+{
+  uint8_t i;
+  uint8_t regN = sizeof(eeprom_addr);
+
+  // read the persistent registers
+  for(i=0; i<regN; ++i)
+    ctl_regs[ eeprom_addr[i] ] = EEPROM_read(i);
+
+  // read the tabke
+  for(i=0; i<tableN; ++i)
+    table[i] = EEPROM_read(regN + i);
+}
+
+
+//------------------------------------------------------------------------------
+//------------------------------------------------------------------------------
+//------------------------------------------------------------------------------
+//
+// Timer0
+//
+
+uint16_t stage1_cnt        = 0;
+uint16_t stage2_cnt        = 0;
+uint8_t  stage1_coarse_cnt = 0;
+uint8_t  stage1_fine_cnt   = 0;
+uint8_t  stage2_coarse_cnt = 0;
+uint8_t  stage2_fine_cnt   = 0;
+uint8_t  hold_beg_first_fl = 0;
+
+volatile uint8_t tmr0_state        = 0;    // current timer mode: 0=disabled 1=coarse mode, 2=fine mode 
+volatile uint8_t tmr0_coarse_cur   = 0;
+
+
+
+
+#define set_attack()    do { ctl_regs[kState_idx] |= kState_Attk_Fl;  PORTB |= _BV(ATTK_PIN);            } while(0)
+#define clear_attack()  do { PORTB &= ~_BV(ATTK_PIN);           ctl_regs[kState_idx] &= ~kState_Attk_Fl; } while(0)
+
+#define clear_hold() PORTB &= ~(_BV(HOLD_PIN))
+#define set_hold()   PORTB |= _BV(HOLD_PIN)
+
+
+void hold_begin()
+{
+  // Reset the PWM counter to to OCR1C (PWM TOP) so that it immediately triggers
+  // set_hold() and latches any new value for OCR1B (See: 12.2.2 Timer/Counter1 in PWM Mode)
+  // If this is not done and OCR1B was modified the first pulse will have the incorrect length.
+  TCNT1   = ctl_regs[kPwm_Freq_idx];  
+  TIMSK  |= _BV(OCIE1B) + _BV(TOIE1);    // PWM interupt Enable interrupts
+
+  TCCR1  |= ctl_regs[ kPwm_Div_idx];     // 32us period (512 divider) prescaler
+  GTCCR  |= _BV(PSR1);                   // Force the pre-scale to be latched by setting PSR1
+  
+}
+
+void hold_end()
+{
+  clear_attack();
+  clear_hold();
+  TIMSK  &= ~_BV(OCIE0A);                // Clear timer interrupt (shouldn't be necessary but doesn't hurt on during note-off message)
+  TIMSK  &= ~(_BV(OCIE1B) + _BV(TOIE1)); // PWM interupt disable interrupts
+
+  TCCR1  = 0;              // Stop the PWM timer by setting the pre-scale to 0
+  GTCCR  |= _BV(PSR1);     // Force the pre-scale to be latched by setting PSR1
+  
+}
+
+// Use the current tmr0 ctl_reg[] values to set the timer to the starting state.
+void tmr0_reset()
+{
+  uint16_t delayCnt = ctl_regs[ kDelay_Coarse_idx ];
+  delayCnt = (delayCnt<<8) + ctl_regs[ kDelay_Fine_idx ];
+
+  uint16_t attkCnt = ctl_regs[ kTmr_Coarse_idx  ];
+  attkCnt = (attkCnt<<8) + ctl_regs[ kTmr_Fine_idx ];
+
+  if( attkCnt > delayCnt )
+  {
+    stage1_cnt = attkCnt - delayCnt;
+    stage2_cnt = delayCnt;
+    hold_beg_first_fl = 1;
+  }
+  else
+  {    
+    stage1_cnt = attkCnt;
+    stage2_cnt = delayCnt - attkCnt;    
+    hold_beg_first_fl = 0;
+  }
+
+  stage1_coarse_cnt = stage1_cnt >> 8;
+  stage1_fine_cnt   = stage1_cnt & 0xff;
+  
+  stage2_coarse_cnt = stage2_cnt >> 8;
+  stage2_fine_cnt   = stage2_cnt & 0xff;
+  
+  tmr0_coarse_cur = 0;               // clear the coarse time counter
+  
+  // always start in mode=1 because even if coarse count==0
+  // because a COMPA interrupt will be fired immediately when the
+  // timer starts
+  tmr0_state = 1;   
+  OCR0A      = 0xff;    
+  TCNT0      = 0;
+
+  clear_hold();   // clear the hold pin
+  set_attack();   // set the attack pin
+  
+  TIMSK |= _BV(OCIE0A);     // enable the timer interrupt
+
+  //if( ctl_regs[ kFlags_idx ] & kHoldOnAttk_Fl )
+  //  hold_begin();
+  
+}
+
+ISR(TIMER0_COMPA_vect)
+{
+  switch( tmr0_state )
+  {
+    case 0: // timer disabled
+      break;
+
+    case 1: // stage1 coarse mode
+      // Note: the '+1' here is necessary to absorb an interrupt which is occurring
+      // for an unknown reason.  It must have something to do with resetting the
+      // OCIE0A interrupt because it doesn't occur on the hold delay coarse timing.
+      if( ++tmr0_coarse_cur >= stage1_coarse_cnt+1 )
+      {
+        tmr0_state = 2;
+        OCR0A      = stage1_fine_cnt;
+      }
+      break;
+
+    case 2: // stage1 fine mode complete
+
+      // if a coarse delay count exists then go into stage2 coarse mode 
+      if( stage2_coarse_cnt > 0 )
+      {
+        tmr0_state      = 3;
+        tmr0_coarse_cur = 0;
+        OCR0A           = 0xff;
+      }
+      else // otherwise go into fine mode
+      {
+        tmr0_state = 4;
+        OCR0A      = stage2_fine_cnt;
+      }
+
+      if( hold_beg_first_fl )
+        hold_begin();  // start hold PWM
+      else
+        clear_attack();
+      
+      break;
+
+    case 3: // stage2 coarse mode
+      if( ++tmr0_coarse_cur >= stage2_coarse_cnt )
+      {
+        tmr0_state = 4;
+        OCR0A      = stage2_fine_cnt;
+      }      
+      break;
+      
+    case 4: // stage2 fine mode complete
+      TIMSK      &= ~_BV(OCIE0A);    // clear timer interrupt
+      tmr0_state  = 0;
+
+      if( hold_beg_first_fl )        
+        clear_attack();
+      else
+        hold_begin();
+      
+      //if( !(ctl_regs[ kFlags_idx ] & kHoldOnAttk_Fl) )
+      //  hold_begin();
+      break;      
+  }
+}
+
+
+
+void tmr0_init()
+{
+  TIMSK  &= ~_BV(OCIE0A);                 // Disable interrupt TIMER1_OVF
+  TCCR0A = 0;                             // Set the timer control registers to their default value
+  TCCR0B = 0;
+  TCCR0A  |=  0x02;                       // CTC mode
+  TCCR0B  |= ctl_regs[kTmr_Prescale_idx]; // set the prescaler
+  GTCCR   |= _BV(PSR0);                   // Trigger the pre-scaler to be reset to the selected value
+}
+
+
+//------------------------------------------------------------------------------
+//------------------------------------------------------------------------------
+//------------------------------------------------------------------------------
+//
+// Pwm
+//
+// PWM is optimized to use pins OC1A ,~OC1A, OC1B, ~OC1B
+// but since these pins are not available this code uses
+// ISR's to redirect the output to PIN3
+
+void pwm1_update()
+{
+  OCR1B   = ctl_regs[kPwm_Duty_idx]; // control duty cycle
+  OCR1C   = ctl_regs[kPwm_Freq_idx]; // PWM frequency pre-scaler
+}
+
+
+// Called when TCNT1 == OCR1C.
+// At this point TCNT1 is reset to 0, new OCR1B values are latched from temp. loctaion to OCR1B
+ISR(TIMER1_OVF_vect)
+{
+  set_hold();
+}
+
+// Called when TCNT1 == OCR1B
+ISR(TIMER1_COMPB_vect)
+{
+  clear_hold();
+}
+
+
+void pwm1_init()
+{
+  DDRB   |=  _BV(HOLD_DIR);  // setup PB3 as output
+  
+  TCCR1 = 0; // Set the control registers to their default
+  GTCCR = 0;
+  GTCCR  |= _BV(PWM1B);    // Enable PWM B and disconnect output pins
+  
+  pwm1_update();
+
+}
+
+//------------------------------------------------------------------------------
+//------------------------------------------------------------------------------
+//------------------------------------------------------------------------------
+
+// Tracks the current register pointer position
+volatile uint8_t reg_position = 0;
+const uint8_t    reg_size = sizeof(ctl_regs);
+
+//
+// Read Request Handler
+//
+// This is called for each read request we receive, never put more
+// than one byte of data (with TinyWireS.send) to the send-buffer when
+// using this callback
+//
+
+void on_request()
+{
+  uint8_t val = 0;
+  
+  switch( ctl_regs[ kRead_Src_idx ] )
+  {
+    case kReg_Rd_Addr_idx:
+      val = ctl_regs[ ctl_regs[kReg_Rd_Addr_idx] ];
+      break;
+
+    case kTable_Rd_Addr_idx:
+      val = table[ ctl_regs[kTable_Rd_Addr_idx] ];
+      break;
+
+    case kEE_Rd_Addr_idx:
+      val = EEPROM_read(ctl_regs[kEE_Rd_Addr_idx]);
+      break;
+
+    default:
+      set_error( kInvalid_Read_Src_ErrFl );
+      return;
+  }
+  
+  usiTwiTransmitByte(val);
+
+  ctl_regs[ ctl_regs[ kRead_Src_idx ]  ] += 1;
+
+}
+
+
+void _write_op( uint8_t* stack, uint8_t stackN )
+{
+  uint8_t stack_idx = 0;
+  
+  if( stackN > 0 )
+  {
+    uint8_t src     = stack[0] & 0x07;
+    uint8_t addr_fl = stack[0] & 0x08;
+
+    // verify the source value
+    if( src < kReg_Wr_Addr_idx  || src > kEE_Wr_Addr_idx )
+    {
+      set_error( kInvalid_Write_Dst_ErrFl );
+      return;
+    }
+
+    // set the write source
+    stack_idx                  = 1;
+    ctl_regs[ kWrite_Dst_idx ] = src;
+
+    // if an address value was passed also ....
+    if( addr_fl && stackN > 1 )
+    {
+      stack_idx       = 2;
+      ctl_regs[ src ] = stack[1];
+    }
+  }
+
+  //
+  for(; stack_idx<stackN; ++stack_idx)
+  {
+    uint8_t addr_idx = ctl_regs[ ctl_regs[kWrite_Dst_idx] ]++;
+    uint8_t val      = stack[ stack_idx ];
+    
+    switch( ctl_regs[ kWrite_Dst_idx ] )
+    {
+      case kReg_Wr_Addr_idx:   ctl_regs[ addr_idx ]           = val;  break;
+      case kTable_Wr_Addr_idx: table[ addr_idx ]              = val;  break;
+      case kEE_Wr_Addr_idx:    EEPROM_write( table[ addr_idx ], val); break;
+
+      default:
+        set_error( kInvalid_Write_Dst_ErrFl );
+        break;
+    }
+  }
+}
+
+//
+// The I2C data received -handler
+//
+// This needs to complete before the next incoming transaction (start,
+// data, restart/stop) on the bus does so be quick, set flags for long
+// running tasks to be called from the mainloop instead of running
+// them directly,
+//
+
+void on_receive( uint8_t byteN )
+{
+  PINB = _BV(LED_PIN);  // writes to PINB toggle the pins
+
+  const uint8_t stackN = 16;
+  uint8_t stack_idx = 0;
+  uint8_t stack[ stackN ];
+  uint8_t i;
+  
+  if (byteN < 1 || byteN > TWI_RX_BUFFER_SIZE)
+  {
+    // Sanity-check
+    return;
+  }
+
+  // get the register index to read/write
+  uint8_t op_id = usiTwiReceiveByte();
+    
+  byteN--;
+
+  // If only one byte was received then this was a read request
+  // and the buffer pointer (reg_position) is now set to return the byte
+  // at this location on the subsequent call to on_request() ...
+  if(byteN)
+  {
+    while( byteN-- )
+    {  
+      stack[stack_idx] = usiTwiReceiveByte();
+      ++stack_idx;
+    }
+  }
+  
+  switch( op_id )
+  {
+    case kSetPwm_Op:
+      for(i=0; i<stack_idx && i<3; ++i)
+        ctl_regs[ kPwm_Duty_idx + i ] = stack[i];
+
+      pwm1_update();
+      break;
+
+      
+    case kNoteOnUsec_Op:
+      for(i=0; i<stack_idx && i<3; ++i)
+        ctl_regs[ kTmr_Coarse_idx + i ] = stack[i];
+
+      // validate the coarse error value
+      if( ctl_regs[ kTmr_Coarse_idx ] > ctl_regs[ kMax_Coarse_Tmr_idx ])
+      {
+        ctl_regs[ kTmr_Coarse_idx ] = ctl_regs[ kMax_Coarse_Tmr_idx ];
+        set_error( kInvalid_Coarse_Tmr_ErrFl );
+      }   
+      // if a prescaler was included then the timer needs to be re-initialized
+      if( i == 3 )
+      {
+        cli();
+        tmr0_init();
+        sei();
+      }
+      
+      tmr0_reset();
+      break;
+
+    case kNoteOff_Op:
+      hold_end();
+      break;
+
+    case kSetReadAddr_Op:
+      if( stack_idx > 0 )
+      {
+        ctl_regs[ kRead_Src_idx ] = stack[0];
+      
+        if( stack_idx > 1 )
+          ctl_regs[ ctl_regs[ kRead_Src_idx ] ] = stack[1];
+      }
+      break;
+
+    case kWrite_Op:
+      _write_op( stack, stack_idx );
+      break;
+
+    case kWriteTable_Op:
+      write_table(); 
+      break;
+
+    case kHoldDelay_Op:
+      for(i=0; i<stack_idx && i<2; ++i)
+        ctl_regs[ kDelay_Coarse_idx + i ] = stack[i];
+
+      break;
+      
+    case kFlags_Op:
+      ctl_regs[ kFlags_idx ] = stack[0];
+      
+  }
+}
+
+
+int main(void)
+{
+  cli();        // mask all interupts
+
+  DDRB  |=   _BV(ATTK_DIR)  + _BV(HOLD_DIR)  + _BV(LED_DIR);  // setup PB4,PB3,PB1 as output  
+  PORTB &= ~(_BV(ATTK_PIN)  + _BV(HOLD_PIN)  + _BV(LED_PIN)); // clear output pins
+  
+  tmr0_init();
+  pwm1_init();
+  
+  // setup i2c library
+  usi_onReceiverPtr = on_receive; 
+  usi_onRequestPtr  = on_request;
+  usiTwiSlaveInit(I2C_SLAVE_ADDRESS);
+  
+  sei();
+
+  PINB = _BV(LED_PIN);  // writes to PINB toggle the pins
+  _delay_ms(1000);  
+  PINB = _BV(LED_PIN);  // writes to PINB toggle the pins
+
+  
+  while(1)
+  {
+
+    if (!usi_onReceiverPtr)
+    {
+        // no onReceive callback, nothing to do...
+      continue;
+    }
+    
+    if (!(USISR & ( 1 << USIPF )))
+    {
+        // Stop not detected
+      continue;
+    }
+
+    
+    uint8_t amount = usiTwiAmountDataInReceiveBuffer();
+    if (amount == 0)
+    {
+        // no data in buffer
+      continue;
+    }
+
+    
+    usi_onReceiverPtr(amount);
+
+    
+  }
+  return 0;
+}
+
+
+

control/tiny/usiTwiSlave.c

@@ -40,13 +40,16 @@ Change Activity:
 /********************************************************************************
                                     includes
 ********************************************************************************/
-
+#include <stddef.h>
 #include <avr/io.h>
 #include <avr/interrupt.h>
 
 #include "usiTwiSlave.h"
 //#include "../common/util.h"
 
+//request_func_t _onTwiDataRequest = NULL;
+request_func_t usi_onRequestPtr = NULL;
+receive_func_t usi_onReceiverPtr = NULL;
 
 /********************************************************************************
                             device dependent defines

control/tiny/usiTwiSlave.h

@@ -36,6 +36,7 @@ Change Activity:
 
 
 
+
 /********************************************************************************
 
                                     includes
@@ -52,17 +53,26 @@ Change Activity:
 
 ********************************************************************************/
 
+
 void    usiTwiSlaveInit( uint8_t );
 void    usiTwiTransmitByte( uint8_t );
 uint8_t usiTwiReceiveByte( void );
 bool    usiTwiDataInReceiveBuffer( void );
-void    (*_onTwiDataRequest)(void);
+//void    (*_onTwiDataRequest)(void);
+
+//extern request_func_t _onTwiDataRequest;
+
 bool    usiTwiDataInTransmitBuffer(void);
 uint8_t usiTwiAmountDataInReceiveBuffer(void);
 // on_XXX handler pointers
-void    (*usi_onRequestPtr)(void);
-void    (*usi_onReceiverPtr)(uint8_t);
+//void    (*usi_onRequestPtr)(void);
+//void    (*usi_onReceiverPtr)(uint8_t);
 
+typedef void (*request_func_t)(void);
+typedef void (*receive_func_t)(uint8_t);
+
+extern request_func_t usi_onRequestPtr;
+extern receive_func_t usi_onReceiverPtr;
 
 /********************************************************************************