Saturday, 25 January 2014

DAB radio module

Leaving the dashboard for a moment and going back to the in-car entertainment, I've noticed that DAB modules are quite expensive. Much more expensive than desktop DAB radios in fact.

I was in Tesco today and saw a DAB alarm/clock/radio for £5. Five pounds. Well, that's got to be worth a poke - even if it lasts 10 minutes before I've blown it up it'll be good value.

Inside there are three boards. The smallest board takes 5V in and offers a headphone out via an 8-pin TSOP amplifier. The largest board runs the MMI and houses the screen and all of the buttons. That's connected via a 14-pin ribbon to the main event - a Gyro-1130E DAB module from GyroSignal Technology Co Ltd.

This FM/DAB module drives the single speaker directly, sends a 5 pin (differential) stereo audio to the headphone amplifier and carries a ton of plated through holes along each of, 14 of which go the MMI board as I mentioned before. The interesting bits are mostly hidden under a large can labelled 'Tunbow', but you can see an FC2507 (PDF) tri-band downmixer from Future Communications Integrated circuit Inc. I might try and lift the can at some point, but there's a whole lot of solder holding it down.

The "Tunbow" label on the can was odd, so I looked it up. It turns out, they make DAB radios and in fact make a radio in an identical case - the a Tunbow E80012. The only difference is in the picture, that has a segmented LCD, whereas mine has a dot matrix (which is actually as described in the specification, so perhaps the picture is just wrong).

Anyway, the audio quality isn't bad and I've seen references to a Gyro-1128 module receive praise in a full-size Audiolab 8200-T DAB receiver. This is quite promising. If I see another, I'll buy it so I can destructively lift the can and see what's underneath.





Monday, 20 January 2014

The dashboard is coming along...

So I can tie input waveform sampling to LCD updates, plus the menu system will reset the various trip values on demand.



What remains is storing the trip values on shutdown, handling day/night mode, tidying up the MMI and making the PCB.

Wednesday, 15 January 2014

Fonts

I've elected to stay with 8-bit mode as I need the pins as GPIO. Text rendering works well provided you are careful to over print a region rather than blanking it first (which causes a flicker).

The fonts came from UTFT. I might patch them to add proportional support but monospace is fine for now. I've knocked up a basic menu system too.

Tired of all the wires the prototype, I ordered some PCBs from OSHpark.com. $50 for three, they should be here any day now.