214 lines
7.7 KiB
Markdown
214 lines
7.7 KiB
Markdown
# ATtiny85 I2C protocol
|
|
|
|
|
|
Arguments in curly braces are optional.
|
|
|
|
------------------------------------------------------------------------------------------
|
|
|
|
__Hold PWM Duty Cycle__
|
|
|
|
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.
|
|
|
|
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
|
|
|
|
------------------------------------------------------------------------------------------
|
|
|
|
__Note-on Velocity__
|
|
|
|
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.
|
|
|
|
------------------------------------------------------------------------------------------
|
|
|
|
__Note-on Microseconds__
|
|
|
|
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)
|
|
|
|
|
|
------------------------------------------------------------------------------------------
|
|
|
|
__Note-off__
|
|
|
|
Function | Opcode | Arguments
|
|
-------------------------|--------|---------------------------
|
|
Note off | 3 | None
|
|
|
|
Turn off a sounding note by settting the hold-voltage to 0.
|
|
|
|
|
|
------------------------------------------------------------------------------------------
|
|
|
|
__Set Read Address__
|
|
|
|
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 Source Id Table_ below for the (src) id values.
|
|
|
|
Arguments | Range | Default | Note
|
|
------------|-------|---------|-------------------------------------------------------
|
|
(src) | 0-2 | n/a | Memory location id. See _Memory Source Id Table_.
|
|
(addr) | 0-255 | n/a | Offset from base address set by (src)
|
|
|
|
Memory Source 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
|
|
|
|
|
|
------------------------------------------------------------------------------------------
|
|
|
|
__Write Memory__
|
|
|
|
Function | Opcode | Arguments
|
|
-------------------------|--------|--------------------------------------------
|
|
Write memory | 5 | (addrFl + dest) {(addr)} (value0) ... (valueN)
|
|
|
|
|
|
Arguments | Range | Default | Note
|
|
------------|-------|---------|----------------------------------------------------------------
|
|
(addrFl) | 0,127 | 0 | Address flag. Set if second byte is an (addr) and not (value0)
|
|
(dest) | 0-2 | n/a | Memory destination location. See _Memory Destination Id Table_.
|
|
(addr) | 0-255 | n/a | Optional offset from base address set by (dest)
|
|
|
|
Memory Destination Id Table
|
|
|
|
Id | Memory | Note
|
|
---|----------------|-------------------------------
|
|
4 | Register file | See register table file
|
|
5 | Velocity table | MIDI velocity to pulse ticks lookup table
|
|
6 | EEPROM | EEPROM data memory
|
|
|
|
------------------------------------------------------------------------------------------
|
|
|
|
__Write Velocity Table to EEPROM__
|
|
|
|
Function | Opcode | Arguments
|
|
-------------------------|--------|---------------------------
|
|
Write velocity table | 6 |
|
|
|
|
Writes the MIDI velocity table from memory to EEPROM.
|
|
|
|
|
|
------------------------------------------------------------------------------------------
|
|
|
|
__Set Hold Delay__
|
|
|
|
Function | Opcode | Arguments
|
|
-------------------------|--------|---------------------------
|
|
Set hold delay | 7 | { 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.
|
|
|
|
------------------------------------------------------------------------------------------
|
|
|
|
__Set *flags* variable__
|
|
|
|
Function | Opcode | Arguments
|
|
-------------------------|--------|---------------------------
|
|
Set flags variable | 8 | (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
|
|
|
|
|
|
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.
|
|
|
|
|
|
------------------------------------------------------------------------------------------
|
|
|
|
|
|
|
|
|
|
|
|
|