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HP-41 GPS Module - True or fiction?
07-19-2017, 10:16 PM (This post was last modified: 07-19-2017 10:19 PM by mfleming.)
Post: #41
RE: HP-41 GPS Module - True or fiction?
Here is the result of a third and likely final iteration of a 41CL version of Ángel's challenge for a GPS module. First, some pictures

[Image: uc?export=view&id=0Bwt5Q_LizRq6bzBIWnJFYUFDdjg]

You'll note the smaller size of the GPS serial board in the upper left hand photo. Smaller than a three AA cell battery pack, the assembly should be a bit more portable. A closeup of the board with a u-blox M8N module and antenna is on the left. Below that is the bare board at about 2" by 2" in size.

The new GPS serial board is based on the more powerful Teensyduino SBC with USB. The real improvement can be seen in the terminal window in the lower left hand corner of the above photo. Connecting the board to USB allows one to set configuration values such as baud rate to the 41CL and the delay in sending characters. Configuration is saved in EEPROM.

An ECHO ON command lets you watch the communication exchange between board and 41CL while debugging a HP-41 program. I'm contemplating adding a feature that will allow you to create new GPS data extraction commands via the USB debug connection rather than altering the Teensyduino code.

Another feature is the CONNECT command that ties the USB serial port to the GPS serial port, allowing a program on your computer to communicate with the GPS module transparently. U-blox has an excellent configuration and display program, as you can see below.

[Image: uc?export=view&id=0Bwt5Q_LizRq6U2llbkZ0ZzBYR0E]

I'm finishing up an article on the GPS serial board that will explain assembly and operation. I'll include all software, Gerber files and bill of materials to build your own board. The whole shebang, including Teensyduino & GPS module, should be under $50 with careful shopping. This project has been quite fun to build and play with. Hope others enjoy it as well.


Remember kids, "In a democracy, you get the government you deserve."
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RE: HP-41 GPS Module - True or fiction? - mfleming - 07-19-2017 10:16 PM

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