New JP1.2/1.3 programmer : Bluetooth

[classicsat]

Reading in a TiVo hacking forum, I found somebody added a Bluetooth module to the debug serial port of a Series 3 TiVo (it has a TTL RS232 header on the system board). I looked into similar modules to what that person used and found they had most of what makes a UART, and ones with just TTL sell for $20 or so. Most claim they had RTS, needed for the JP1.2/JP1.3 remotes, to put the remote into serial mode, so I thougt, would they work with JP1.2/1.3? Such would go along nicely with my legacy port free netbook computer, which has Bluetooth built in.

So, I went and bought a couple (similar hardware Bluecore 4 based modules). And waited from them to come from China

The first was unfortunately firmware locked to 9600 baud (it was a Sure Electronics GP-GC021; the vendor did not make the 9600 thing particularily clear).

The second (A CuteDigi BMX Bluteooth to UART, sold by Emartee) was rather open (programmable with AT commands). Despite the claims of the vendor, RTS did not apparently work.

The module does however have a GPIO (GPIO 9) which goes high (when a application goes to use it (at least is my observation on Windows 7),and can be programmed to go low with an AT command in setup mode.

I have figured out a circuit, with a .1uf poly capacitor from that GPIO line (set to go positive when active, and with an LED connected per datasheet, except with 470 ohm resistors), to a basic NPN transistor inverter through a 3.3K base resistor, a 5.1K pullup on the collector (to JP1.2/1.3 Reset), emitter to ground, and an LED and resistor on the GPIO line (as per the module doumentation. Module TX and RX (pulled up with 5.1K resistors) connect to JP1.2/1.3 RX/TX. Power, so far, as come from 3x1.2V AA cells

Parts values are just close values pulled of junk boards, the circuit built on a perf board, the BT module (1.5mm pin pitch) extended with wires to the 0.1" perf boar, and to raise the board enough so the antenna would not get de-tuned.

More info and datasheets on the module are at Emartee.

To do, is try and power it from the remote, with an additional AAA or similar battery (the Sure Electronics module would not work off of 2x1.2V NiMH AAA batteries, I can assume the Emartee one would be the same, since both use the same BC4 chip), see if I can eliminate the inverter by setting GPIO9 to active low, and figure a spiffy case for it.

[The Robman]

The one thing that's not clear from your message is whether it actually worked or not. So, could you get it to download the E2 space from the remote?

If it does work, I see a collaboration with Tommy Tyler in your near future!

[classicsat]

I can read the remote. Or at least could until I started tinkering with the circuit. It didn't want to write. The remote is an 8820.