Tuning Fork Clock Firmware

This repository contains the firmware for the Tuning Fork Clock.

The Makefile can build a .hex file and also flash it to the chip using avrdude using make flash.

Running make fuses will set all the correct fuse bits on the controller using avrdude.

Serial Protocol

The firmware exposes a serial interface at 9600 baud which allows you to remotely configure the clock.

Available Commands

All commands consist of a single upper case letter specifying an option directly followed by a value or a question mark and terminated with a newline.
Passing a value will set the option to that value, passing a question mark will return the current value of that option.

Note that some options are read-only or write-only.

Each command is followed by a line beginning with an equals sign followed either by the letters OK or ERR.
The error response is followed by an error code.

E

Controls echoing of characters. This value is write only.

• E0\n - Disable echoing
• E1\n - Enable echoing

A

Controls automatic time sending. This value is write only.

When enabled the current time will be sent via serial port each second.

• A0\n - Disable automatic time sending
• A1\n - Enable automatic time sending

C

Controls the charset. This value is write only.

• C0\n - Use PAWScript
• C1\n - Use normal boring numbers

T

Controls the current time.

When read it returns the current time with second accuracy, when written it only accepts hours and minutes.

• T?\n - Returns the current time in HH:MM:SS format
• T12:34\n - Set the time to 12:34

P

Controls the pulses per minute setting.

• P?\n - Returns the current pulses per minute setting
• P26400\n - Set the time to 26400

M

Retrieves the mode of the clock. This value is read-only.

• M?\n - Returns the current mode the clock is in

Possible Modes:

• D - Time display mode
• H - Hour setting mode
• M - Minute setting mode
• T - Pulses per minute tuning mode
• E - Error mode due to loss of tuning fork signal or other error

R

Controls the "run" state of the clock. It is not possible to stop the clock with this command.

• R?\n - Returns 0 or 1 depending on if the clock is current running or not
• P1\n - Sets the clock running, clearing any errors or time-set modes

Error Codes

• :UC - Unknown command
• :INV - Invalid command parameter