app/README.md,tiny/README.md,ctrl/READM.md : Initial commit.

control/README.md

 
 The _picadae_ control program consists of three parts:
 
-- _tiny_ : Keyboard solenoid driver
-- _ctrl_ : Keyboard central controller
-- _app_  : Monitor and command utility.
+- _tiny_ : [ATtiny85 solenoid driver firmware](tiny/README.md)
+
+- _ctrl_ : [ATmega328 interface unit](ctrl/README.md) 
+
+- _app_  : [Python monitor and command utility](app/README.md)
 
 # Architecture
 
-The keyboard control hardware consists of 8 driver boards
-mounted above the solenoids on the keyboard assembly.
-Each driver board has 11 key driver circuits and can
-therefore control 11 piano keys. Each key driver
-circuit consists of an ATtiny85 microcontroller
-which controls a set of power transistors
-which in turn control the state of the solenoid.
+The keyboard control hardware consists of 8 driver boards mounted
+above the solenoids on the keyboard assembly.  Each driver board has
+11 key driver circuits which control 11 piano keys. Each key driver
+circuit consists of an ATtiny85 microcontroller which controls a set
+of power transistors which in turn control the state of the solenoid.
 The solenoid can be in one of three states:
 
 - off
 the solenoid with a fast (250 microsecond to
 30 millisecond) 36 volt pulse. The duration
 of the pulse determines the attack dynamic.
-The hold state then holds the key down
-during the sustain portion of the note.
+Longer pulses produce louder notes.
+At the end of the attack state the solenoid
+transitions into a hold state. During
+this time the key is held down with just
+enough force to sustain the note.
 
 All 88 ATtiny85 microncontrollers are attached
-to a single I2C bus which is shared with
-an Arduino Uno.  The application computer
-communicate with the Uno via 
-a serial connection. The Uno in turn
-translates messages between the 
-ATtiny85 channel computers and the
-application computer.
-
-# Keyboard central controller : Arduino Uno Serial Interface
+to a single I2C bus which is mastered by an ATmega328 MCU
+which acts as a serial to I2C translator for the host computer.
 
-Read a register value of `<count>` bytes from channel `<i2c-addr>`
+The host API is implemented as the Python class 'Picadae' in app/picadae_api.py.
+The control shell program app/picadae_shell.py shows an example
+usage of the API.
 
-    'r' <i2c-addr> <register> <count>
-	
-Write a register value of `<count>` bytes from channel `<i2c-addr>`
 
-	'w' <i2c-addr> <register> <count> <value-0> <value-1> ... <value-n>
 
+ 
 
-# Keyboard solenoid driver : ATtiny85 Firmware
 
 
-PWM counter frequency and period.
-for each possible `div` setting
-with 16 Mhz system clock.
 
-Value | Div  | Frequency   | Period
-------|------|-------------|-------
- 1    |    1 |    16    M  | 62.5 n 
- 2    |    2 |     8    M  |  125 n
- 3    |    4 |     4    M  |  250 n
- 4    |    8 |     2    M  |  500 n
- 5    |   16 |     1    M  |    1 u
- 6    |   32 |   500    K  |    2 u
- 7    |   64 |   250    K  |    4 u
- 8    |  128 |   125    K  |    8 u
- 9    |  256 | 62500    Hz |   16 u
-10    |  512 | 31250    Hz |   32 u
-11    | 1024 | 15625    Hz |   64 u
-12    | 2048 | 7812.5   Hz |  128 u
-13    | 4096 | 3906.25  Hz |  256 u
-14    | 8192 | 1953.125 Hz |  512 u
-15    |16384 | 976.6625 Hz | 1024 u 
 
 
-# Monitor and command utility : Python Utility
 
 
 

control/app/README.md

+# Picadea control and monitor shell

control/ctrl/README.md

+# ATmega328 Interface Unit
+
+This MCU acts as a serial to I2C translator for the host
+computer.  The serial protocol implements two
+interfaces.  One for read requests and another for write commands.
+
+The data format of the write commands is given
+in the ATtiny85 I2C protocol document.
+
+Read requests return blocks of memory begining with the address
+specified in the last 'Set read address' command.
+
+## Read: Channel to Host
+
+Read a `<count>` bytes from a channel beginning at offset = 'offset'
+
+    'r' <i2c-addr> <offset> <count>
+
+## Write: Host to Channel
+
+Write `<count>` bytes from from the host to a channel
+
+    'w' <i2c-addr> <register> <count> <value-0> <value-1> ... <value-n>

control/tiny/README.md

+# ATtiny85 I2C protocol
+
+
+Arguments in curly braces are optional.
+
+
+Function                 | Opcode | Arguments
+-------------------------|--------|---------------------------
+Set hold PWM duty cycle  |    0   | (duty) { (freq) { (div) }}
+
+Arguments | Range | Default | Note
+----------|-------|---------|------------------------------------------------------
+(duty)    | 0-255 |    127  | 0=0%, 255=100%
+(freq)    | 0-255 |    255  | Sets PWM top value
+(div)     | 1-15  |      5  | Set the PWM base clock frequency (See table below) 
+
+PWM frequency and period for each possible (div) setting.
+
+Reg.  |      | Base        | 
+Value | Div  | Frequency   | Period
+------|------|-------------|-------
+ 1    |    1 |    16    M  | 62.5 n 
+ 2    |    2 |     8    M  |  125 n
+ 3    |    4 |     4    M  |  250 n
+ 4    |    8 |     2    M  |  500 n
+ 5    |   16 |     1    M  |    1 u
+ 6    |   32 |   500    K  |    2 u
+ 7    |   64 |   250    K  |    4 u
+ 8    |  128 |   125    K  |    8 u
+ 9    |  256 | 62500    Hz |   16 u
+10    |  512 | 31250    Hz |   32 u
+11    | 1024 | 15625    Hz |   64 u
+12    | 2048 | 7812.5   Hz |  128 u
+13    | 4096 | 3906.25  Hz |  256 u
+14    | 8192 | 1953.125 Hz |  512 u
+15    |16384 | 976.6625 Hz | 1024 u 
+
+
+Function                 | Opcode | Arguments
+-------------------------|--------|---------------------------
+Note on velocity         |    1   | (vel)
+
+Arguments | Range | Default | Note
+----------|-------|---------|------------------------------------------------------
+(vel)     | 0-127 |  n/a    | Note on velocity.
+
+Execute a note onset.
+The (vel) value is translated to an attack pulse duration
+by looking up the pulse tick count in the velocity table.
+
+
+Function                 | Opcode | Arguments
+-------------------------|--------|-------------------------------------------------
+Note on ticks            |   2    | (pulse-ticks-high-byte) (pulse-ticks-low-byte)
+
+Execute a note onset.
+The 16 bit attack duration in ticks is calculated from microseconds.
+
+    pulse-ticks = (usec / 1e6) * (16e6/256)
+
+Where 16e6 is the system clock frequency and 256 is the timer0 clock divider.
+`TCCR0B:C02,C01,C00 = 100b (4)`
+
+
+ticks to micoseconds:
+
+    usecs = (pulse-ticks * 1e6)*(256/16e6)
+
+
+Function                 | Opcode | Arguments
+-------------------------|--------|---------------------------
+Note off                 |   3    | None
+
+Turn off a sounding note by settting the hold-voltage to 0.
+
+
+Function                 | Opcode | Arguments
+-------------------------|--------|---------------------------
+Set read address         |    4   | (src) {(addr)}
+
+Set the source and address of the next I2C read request.
+
+The read can come from one of three memory banks:
+Register File, MIDI velocity table or EEPROM.
+See the _Memory Location Id_ table below for the (src) id values.
+
+
+Arguments   | Range | Default | Note
+------------|-------|---------|-------------------------------------------------------
+(src)       | 0-2   |  n/a    | Memory location id. See _Memory Location Id_ table.
+(addr)      | 0-255 |  n/a    | Offset from base address set by (src)
+
+
+Function                 | Opcode | Arguments
+-------------------------|--------|---------------------------
+Write memory             |    5   |
+
+
+
+Function                 | Opcode | Arguments
+-------------------------|--------|---------------------------
+Set hold delay           |    6   | { high {low}}
+
+Set the length of the delay, in ticks, between when the attack pulse ends and when the
+hold voltage is applied.
+The high and low byte values are calculated identically to the
+attack pulse duration values.
+
+
+Function                 | Opcode | Arguments
+-------------------------|--------|---------------------------
+Set flags variable       |    7   | (flags)
+
+  7  |  6  |  5  |  4  |  3  |  2  |  1  |  0  
+-----|-----|-----|-----|-----|-----|-----|-----
+ n/a | n/a | n/a | n/a | n/a | n/a | n/a | HOA
+
+_HOA_ : Set to apply the hold voltage at the beginning of the attack.
+
+
+Register file
+
+Address | Label           | Note
+--------|-----------------|------------------------------------------------------------------------------------------------
+0       | Reg_Rd_Addr     | Next register file address to read.
+1       | Table_Rd_Addr   | Next MIDI velocity address to read.
+2       | EEPROM_Rd_Addr  | Next EEPROM address to read.
+3       | Read_Src_Addr   | Source of the next I2C read request. See Memory Location Id table below.
+4       | Reg_Wr_Addr     | Next register file address to write.
+5       | Table_Rd_Addr   | Next MIDI velocity address to write.
+6       | EEPROM_Rd_Addr  | Next EEPROM address to write.
+7       | Write_Dst_Addr  | Destination of the next 'write operation'. See Memory Location id table below.
+8       | Tmr_High_Addr   | Current attack pulse tick count high byte
+9       | Tmr_Low_Addr    | Current attack pulse tick count low byte
+10      | Tmr_Div_Addr    | Attack pulse counter frequency divider.
+11      | Pwm_Duty_Addr   | Duty cycle of the hold PWM generator
+12      | Pwm_Freq_Addr   | PWM counter max values. Determines the PWM frequency.
+13      | Pwm_Div_Addr    | PWM clock divider
+14      | State_Addr      | Current solenoied state.
+15      | Error_Addr      | Error status
+16      | Max_Tmr_Hi_Addr | Max attack pulse high byte tick count.
+17      | Delay_High_Addr | Hold delay onset tick count high byte
+18      | Delay_Low_Addr  | Hold delay onset tick count low byte
+19      | Flags_Addr      | Binary variable field.
+
+
+Memory Location Id table.
+
+Id | Memory         | Note
+---|----------------|-------------------------------
+ 0 | Register file  | See register table file
+ 1 | Velocity table | MIDI velocity to pulse ticks lookup table
+ 2 | EEPROM         | EEPROM data memory
+
+
+
+