THIS PROJECT HAS MOVED

This project has been merged into the larger "Jessie" repository. You can find it at https://github.com/scy/jessie

Mr. Homn

This is the software running on Jessie’s Arduino Mega controlling switches and relays.

Status

I'm in a bit of a hurry. Documentation will improve.

• done
  • interrupt-driven main loop that blinks the on-board LED in a heartbeat animation (proud of the keyframe array based implementation)
  • handling of button/switch input and relay output
• to do
  • UART handling and commands
  • UART heartbeat and host heartbeat checking

Bugs and Quirks

• It might behave unexpectedly if you configure it to have no input or no output port.
• Because of optiboot#177, building optiboot_atmega1280.hex from source might not be possible easily on your system. Luckily, that file is provided as a complete binary in the Optiboot repo, so we can simply copy it. The problem with compiling seems to be the EEPROM writing; you should be able to build it if you don't enable -DBIGBOOT, but the Optiboot makefile won't let you (CFLAGS is overridden, DEFS (where you could do -UBIGBOOT) comes before the builtin -DBIGBOOT).

How to Flash

Use make clean flash to flash it to the Duemilanove. Use make MCU=atmega1280 clean flash to flash it to the Mega. If you want to flash the output test routine instead of the normal button behavior, use make FLAGS=-DDO_OUTPUTTEST clean flash (combined with MCU=atmega1280 for the Mega).

Tested on Debian Stretch. You can use make install-deps to install avr-libc and avrdude.

Hardware Specs and Limits

I'm using six C-Control relay boards (Conrad SKU 1488848) with 4 relays on each one. These can run on 12V DC, the Arduinos as well. Each relay can switch up to 30V DC or 250V AC, both up to 10A, and each board eats up to 20 mA power.

Since I didn't specify my needs well enough to the company that built the van's interior, the physical push buttons in my furniture supply 5V when pushed instead of connecting to ground, i.e. they are active high. This keeps me from using the AVR's internal pull-up resistors; I had to build external pull-downs instead. The software supports both, depending on whether the constant ACTIVE_HIGH is defined when building. The Makefile defines it by default.

Port/Pin Mapping

This code is designed to run on two devices: An Arduino Duemilanove (MCU=atmega168) that I use for testing and an older Arduino Mega (MCU=atmega1280) that's built into the van (read: the production system).

Since the two controllers have a different number of ports, there is no universal pin mapping for both. Instead, each one has its own.

For easier handling in the code (array indexes!), I map the AVR port names (A, B, C etc.) to numbers internally. To simplify things further, each port on the Mega is only used for input or for output, i.e. I won't use four pins as input and four as output. This is not true for the Duemilanove: Since it only has three ports, I had to use port B for both input and output in order to let it have two input and two output ports.

Not all pins of a port are necessarily available for GPIO, for example if they're the UART pins.

On the Duemilanove

Port	Usage	Notes
B	In 1/Out 1	(pin 0 input, labelled Digital 8; pin 1 and 2 output, labelled Digital 9 and 10)
C	In 0	(low 6 pins only, labelled Analog In 0 to 5)
D	Out 0	(high 6 pins only, labelled Digital 2 to 7)

That's 7 inputs and 8 outputs. I haven't used PB3 to PB5 (digital 11 to 13), since they double as ISP ports.

On the Mega

The ports are kind of a mess here. Some are scattered all over the board, others are labelled in the opposite direction (i.e. pin 0 labelled 37, pin 7 labelled 30). I've tried to reflect this in the table below.

Port	Usage	Notes
A	Out 0	(labelled Digital 22 to 29)
B	In 1	(low 7 bits only, labelled Digital 53 to 50 and PWM 10 to 12)
C	Out 1	(labelled Digital 37 to 30)
F	reserved	(labelled Analog In 0 to 7) reserved for actual analog input
G	In 2	(low 3 pins only, labelled Digital 41 to 39)
K	In 0	(labelled Analog In 8 to 15)
L	Out 2	(labelled Digital 49 to 42)

That's 18 inputs and 24 outputs, with 8 pins reserved for analog input (e.g. temperature or water tank). I haven't used PB7 (digital 13), since it doubles as the LED.

Ribbon Cable

I'm using a 40-wire rainbow ribbon cable by Joy-IT (RB-CB2-030) to connect the 2x18-pin female port of the Mega to six 4-relay boards and some inputs. The great thing with this cable is that on one end it ends in 40 single Dupont jacks that can easily be removed from their plastic housing and grouped together as you wish. However, since the IDE-style connector it has at the other end is female as well, it doesn't couple nicely with the Mega. (It's certainly made for a Raspberry Pi's GPIO pins.)

To work around that, I've crimped a cutting 40-pin male IDE connector to the end of the cable directly adjacent to the female one. When you remove some of its plastic housing, it fits nicely on the Mega, even though two pins on either side stay unconnected.

These are the pins of the Mega's port and how they map to the cable and the peripherals connected to it. It's ordered by the wires on the cable (the color column).

Pin	Type	Internal	Label	Color	Relay	Connected To
				black
				white
			5V	gray
			5V	purple
PA1	Out	0,1	23	blue	1-2	drinking water pump
PA0	Out	0,0	22	green	1-1	main water pump
PA3	Out	0,3	25	yellow	1-4
PA2	Out	0,2	24	orange	1-3
PA5	Out	0,5	27	red	2-2
PA4	Out	0,4	26	brown	2-1
PA7	Out	0,7	29	black	2-4
PA6	Out	0,6	28	white	2-3
PC6	Out	1,6	31	gray	4-3
PC7	Out	1,7	30	purple	4-4
PC4	Out	1,4	33	blue	4-1
PC5	Out	1,5	32	green	4-2
PC2	Out	1,2	35	yellow	3-3
PC3	Out	1,3	34	orange	3-4
PC0	Out	1,0	37	red	3-1
PC1	Out	1,1	36	brown	3-2
PG2	In	2,2	39	black		sink (foot switch)
PD7			38	white
PG0	In	2,0	41	gray		sink (faucet)
PG1	In	2,1	40	purple		shower
PL6	Out	2,6	43	blue	6-3
PL7	Out	2,7	42	green	6-4
PL4	Out	2,4	45	yellow	6-1
PL5	Out	2,5	44	orange	6-2
PL2	Out	2,2	47	red	5-3
PL3	Out	2,3	46	brown	5-4
PL0	Out	2,0	49	black	5-1
PL1	Out	2,1	48	white	5-2
PB2	In	1,2	51	gray		free input
PB3	In	1,3	50	purple		free input
PB0	In	1,0	53	blue		free input
PB1	In	1,1	52	green		free input
			GND	yellow
			GND	orange
				red
				brown