USB For Your Digital Setting Circles
October 21st, 2007 by Dave
Jimbo Harris was good enough to tell me about his USB modification of my digital setting circles project. Jim found the FTDI TTL232R and was able to adapt his DSC interface to communicate via (and draw power from) the USB port.
Jim wrote to me:
“Hi Dave,
The TTL232 modification was a success; I connected to the board in place of the MAX232 at pins:
+5v - pin 16
GND - pin 15
Tx - pin 11
Rx - pin 12
(all corresponding pins of the MAX232), and I left out the MAX232, 7805, and all the corresponding caps, etc. The interface booted right up. I connected via both your program and also via the ASCOM driver (in ASCOM Validator and in DSLR Focus). I got the same results both ways.”
Here’s the marked-up schematic that Jim sent me:
Jim also sent me a photo of the TTL232R kit:
And here’s a picture of his connection of the TTL232R to the interface board:
This entry was posted on Sunday, October 21st, 2007 at 6:03 pm and is filed under Digital Setting Circles. This post has 1,012 views. You can follow any responses to this entry through the RSS 2.0 feed. You can skip to the end and leave a response. Pinging is currently not allowed.
December 1st, 2007 at 6:42 am
Hello David,
Do you know if for this modification Jimbo used the TTL-232R-3V3 or the TTL-232R?
They have different specifications in the Vcc.
Thank you.
December 1st, 2007 at 8:58 am
Hi George,
I wrestled with this same question before purchasing.
I decided to go with the 5v version of the unit instead of the 3.3v (3V3) version, since the original circuit had a 7805 5V regulator in it (U1).
There are also several styles of the 5V version. I got the “base” model, not the “AJ” (audio jack) or “PCB” version.
I happened to order from Mouser (it’s available elsewhere, too). The (complete) Mouser part number is: 626-DLP-TTL232R
Keep looking up,
Jimbo
April 9th, 2008 at 9:11 pm
i am curious and new to electronics in general but i am following and starting a project using a palm device for my DSC using this board. there seems to be some concern about the board eating 9v batteries does this adaptation cure this problem and if so how to i get it. i have not ordered anything yet to begin. just got the palms and some of the info to build.
doc
April 9th, 2008 at 9:22 pm
James,
Nope, this won’t improve battery life. It must means that you can connect it to a PC’s USB port instead of a serial port. Since you’re talking about a Palm device, this modification won’t work for you. For improved battery life, I recommend you use a sealed lead-acid battery (sometimes called a gell cel. You can often get them surplus for not a lot of money.