MikonaFirmware

Mikona firmware running on its local PIC processor.

I2C Protocol

Mikona exposes a register-based I2C slave interface. All transactions begin with a register address byte, followed by data bytes to write or read.

Device ID: 0x54

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Register Map

Address	Name	Access	Description
0x01	DEV_ID	Read	Device identification byte (0x54)
0x02	STATUS	Read/Write	Status and control flags
0x03	V_OUT	Read	Capacitor voltage (scaled, see below)
0x04	KICK_A	Write	Fire solenoid A (2 bytes)
0x05	KICK_B	Write	Fire solenoid B (2 bytes)
0x06	FAULT	Read/Write	Fault cause bitfield

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STATUS Register (0x02)

Bit:  7  6  5  4  |  3   |  2  |    1    |   0
      X  X  X  X  |FAULT |DONE |DISCHARGE|CHARGE

Bit	Name	R/W	Description
0	CHARGE	R/W	Set 1 to start charging capacitors. Clear to stop.
1	DISCHARGE	R/W	Set 1 to discharge capacitors.
2	DONE	R	1 when capacitor voltage is within 10V of the learned peak.
3	FAULT	R	Summary fault flag. Read-only — clear by writing 0x00 to FAULT register.

Write mask: bits 0 (CHARGE) and 1 (DISCHARGE) only. Bits 2 (DONE) and 3 (FAULT) are read-only.

Charging behavior

The firmware maintains capacitor charge automatically:

1. Master sets CHARGE=1 to begin the first charge cycle.
2. Once the IC signals done, the firmware records the peak voltage.
3. If voltage drops more than 10V below the learned peak, a new charge cycle is triggered automatically — no action required from the master.
4. DONE=1 means the capacitors are charged to near-peak voltage; DONE=0 means a charge cycle is in progress.
5. Set CHARGE=0 to stop charging entirely.

The learned peak voltage is the median of the last 5 charge-done readings, providing noise rejection.

Invalid command combinations

The following combinations are rejected and set FAULT:

• CHARGE=1 and DISCHARGE=1 simultaneously.
• Sending a KICK_A or KICK_B command while DISCHARGE=1.

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V_OUT Register (0x03)

Read-only. Capacitor voltage scaled as:

V = register_value * (4.096 * 101 / 1023) volts

The register saturates at 255. Updated continuously via ADC interrupt.

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KICK_A / KICK_B Registers (0x04, 0x05)

Write-only, 2 bytes. Writing a non-zero 16-bit value fires the corresponding solenoid for the specified pulse duration. The two bytes must be written in a single I2C transaction.

Kick A and Kick B are mutually exclusive at the hardware level — issuing one disables the other's output pin.

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FAULT Register (0x06)

Bit:  7  6  5  |       4        |       3        |        2        |       1        |      0
      X  X  X  |KICK_B_NO_DROP  |KICK_A_NO_DROP  |DISCHARGE_STUCK  |CHARGE_TIMEOUT  |INVALID_CMD

Bit	Name	Description
0	INVALID_CMD	Invalid command: charge+discharge simultaneously, or kick while discharging.
1	CHARGE_TIMEOUT	Charge cycle did not complete within 5s. Possible causes: disconnected capacitor, failed IC.
2	DISCHARGE_STUCK	Voltage did not drop by 5V per second during discharge. Possible causes: stuck FET, open circuit.
3	KICK_A_NO_DROP	Voltage did not drop by 10V within 50ms of kick A. Possible causes: stuck FET, open circuit.
4	KICK_B_NO_DROP	Voltage did not drop by 10V within 50ms of kick B. Possible causes: stuck FET, open circuit.

Multiple bits may be set simultaneously. The FAULT bit in the STATUS register is a summary flag set whenever any fault bit is set.

To clear: write 0x00 to the FAULT register. This clears all fault bits, the STATUS.FAULT flag, and restores the green LED.

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LED Indicator

Color	Meaning
Green	Normal operation
Red	Fault detected — read FAULT register for cause