Video Hardware

First up, the video hardware, not just because it's the most straightforward to get a quick result out of, but also because it's where my first tv-out experiment fell down. The Humane-PC's video output is based on the Tellymate from Batsocks, it too is open source as well as being a very clever idea, so that's where I headed and started studying the schematics.

If you've scavenged an ATMega328p from somewhere else, then the Arduino bootloader needs to be overwritten by the Tellymate firmware. My first try resulted in failure but I had negated to alter the ATMega's fuse bit settings as necessary before programming the firmware.

I'm using an external crystal and caps for the oscillator, so I executed the following to set the bits:

avrdude -p m328p -c avrisp -P /dev/ttyUSB0 -b 19200 -v -e -U lfuse:w:0xff:m -U hfuse:w:0xd9:m -U efuse:w:0x07:m

Then flashed the firmware with:

avrdude -p atmega328p -P /dev/ttyUSB0 -c avrisp -b 19200 -U flash:w:TellyMate_M328p.hex

Programming an ATMega328p with the Tellymate firmware using my home-made AVRISP programmer atop my trusty Duemilanove.

Insert a finger in each ear and connect the battery :). Ready to test...

yAy! - Second time lucky - Plugging a tiny microcontroller project into a 42" tv is overkill to say the least. Will have to see if I can lay my hands on a mini tv or something, I can't keep switching Jeremy Kyle off just to try out my latest sketch, can I?.

Nice and sharp too, I put the 2x 100nf caps that Batsocks specify between pins 7 & 8 and pins 20 & 22 on the ATMega, dunno if they make any difference - guess I'll find out when I remove them.