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Flash with 2.5mm Headphone Jack
01-30-2015, 11:11 PM (This post was last modified: 02-10-2015 06:29 AM by BarryMead.)
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Flash with 2.5mm Headphone Jack
A while back Marcus von Cube posted a thread on how to flash a WP-34S with a 2.5mm headphone jack. here This posting is similar to his with a few simplifications. I decided to mount the 2.5mm headphone jack in the center of the calculator along the top edge. With this mounting arrangement it is easier to cut away the plastic of the case to make room for the jack, and you don't need to cut away any of the mounting struts. Since I already owned one of the FTDI TTL-232R-3V3-AJ cables from another project my cost to build was less than with Harald Pott's USB board. See the attached photos. There is one advantage to this connector over the USB connector. If you have two or more calculators built in this way, you can use a 2.5mm crossover cable to transfer programs and data directly from one calculator to the other without a computer. The spreadsheet shows two extra SMT capacitors, because they seem to go flying across the room when I try to hold them with a pair of tweezers.
The connections are:

1. Tip (USB Cable TX) goes to JP5 (Calculator RX)
2. Ring (USB Cable RX) goes to JP6 (Calculator TX)
3. Sleeve (USB Cable Gnd) goes to Battery Minus (Calculator Gnd)

The attached spreadsheet shows where to order everything to make your own WP-34S with the 2.5mm headphone jack. If you order everything it costs more than with Harald's USB board, but I already owned the cable so it cost less in my case.

Attached File(s)
.xls  BOM-Serial.xls (Size: 14.5 KB / Downloads: 28)
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Flash with 2.5mm Headphone Jack - BarryMead - 01-30-2015 11:11 PM

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