Re: TT4BT or splitter cable
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There is another way to add BT to a TT4 with a socketed MAX232 chip (kit version for sure). The catch is that you must switch to TTL for both serial devices (GPS and computer interface).
Buy a cheap BT HC-05 (or SC-HC-08 for BT 4.0).? Most come with 3.3V regulator for 5V into the board, but double check.
Program the BT module as needed before installation, as there is no longer a 'program' jumper. ?? You will need to remove the BT module to make any changes to the settings
?? I use a cheap CP2102 module. I used a separate, machined DIP socket and installed the components into that for easy change between RS232 and BT/TTL.
Remove the MAX232 and jumper the secondary (Rx2/Tx2), pins 7<->10 and 8<->9. Port B is now TTL ONLY!
Then jumper the 4 pins of the BT module to the socket 5V, Gnd, TLL 1 out, and TLL 1 in - check your MAX232 pinout for exact pins. ?? Or solder to the new socket spots.
You probably will need a new case, as there doesn't seem to be room inside for the module.
The nice feature is the larger case will likely have room for a u-Blox TTL GPS module.?? ?? You can connect this to the the TTL level Rx2/Tx2 and then everything is in the same case
Robert Giuliano KB8RCO
On Monday, July 31, 2023 at 04:57:27 AM EDT, Barry L. Lankford <barryl@...> wrote:
Greg,
If you're interested in making your own TT4BT, I have a schematic for it, and the parts appear to be pretty easy to come by.? I was a beta tester for the TT4 way back then (15 to 20 years ago, I'd guess).? More recently, when the TT4 and its accessories became available as Byonics products, I ordered a TT4BT for my beta TT4.? As I like having schematics for my electronics equipment; I believe Byon's documentation for the TT4BT didn't include a schematic for the Blue Tooth adapter.? So I did a little "reverse engineering" and made my own using the schematic capture software that you can get free from ExpressPCB.? I'm pretty sure I uploaded the schematic as a PDF or JPG to the original Yahoo TT4 group (or it may have been the special "TT4 Beta" Yahoo group).? Anyway, I did a cursory search for it on this group, and couldn't find it.? I'm pretty sure it's still on one of my computers.?
I've grown quite a bit older since those days, and eyesight, short-term memory and age have taken their toll, so searches are tiresome.? But I'm pretty sure it's still on one of my several computers, and I can probably find it easily enough by doing a global search on each computer for the word "ExpressPCB."
The parts should be easily obtainable and cheap, but it'd probably cost as much as the finished product from Byonics (if it becomes available again).? There are two DE-9 connectors (one of each gender), a 3.3v linear voltage regulator (probably an LDO type), a 4-port logic level shifter (a MAX232-something part), an HC-05 Bluetooth master/slave module, a couple of LEDs, and a handful of resistors and small caps, and a two-pin header and jumper (for the program/run function of the HC-05.? I've never gotten into surface mount except for assembling some small kits (come to think of it, I believe the beta TT4 TinyTrak itself has some surface mount parts and it was a kit), so, although the production TT4BT has surface mount versions of the regulator and the level-shifter ICs, I'd buy the leaded versions of those parts, mount them on perfboard and wire them up using 2 or 3 turns of kynar-insulated wire-wrap #30 wire on standard solder-length pins, and then melt a little solder on each of the wire-wrap connections (to keep from having to have terminations with the inconveniently long 0,025" square pins).? There aren't many wires (nodes in the netlist) involved in the circuit, so it isn't a lot of work. You may have better ways of wiring it up (such as getting a PC board made), but this has long been my way.
I've never made a hand-wired copy of the TT4BT, so I can't assure you that making your own will work, but I'm pretty sure the wiring and parts are correct on my schematic, but there might be something I've missed or forgotten, such as, what configuration needs to be made to the HC-05 that Byon might have pre-configured?? BTW, there's documentation for the HC-05 module available online.? Just Google "HC-05"
If you want to try? it, or if you're just curious, let me know and I'll hunt it down, and shoot you a copy.
73,
Barry
N4MSJ
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