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Alternative WP34S flashing using Arduino - Printable Version

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RE: Alternative WP34S flashing using Arduino - zelez - 12-01-2014 06:35 PM


anetzer say:
"Just wanted to thank you for the very readable and practical instructions. I got my hands on an Arduino and managed to flash a handful of 20B's in practically no time."

I have same experience.
I've just flash two hp20b calculators
using Arduino Duemilanove.
Works like a charm.
Thank you for sharing idea and excelent manuals.


RE: Alternative WP34S flashing using Arduino - mendesp - 12-15-2014 06:09 PM

Thank you for these instructions. Since I can't flash my calculator, I was wondering if this is because my Arduino nano clone is equiped with a CH340G chip instead of the genuine FTDI ?

Anyone having success with a CH340G ?



RE: Alternative WP34S flashing using Arduino - subaffo - 12-07-2015 09:27 AM


I was preparing my Arduino (One) to flash a 20b but then I stopped:

the Tx,Rx levels are at 5V, not at 3.3V.

I haven't seen any resistor on those lines in the schematics.
Most of the Arduino boards are at 5V levels.

Did I miss something in the (fine) documentation of this flashing method?

Thanks to all


RE: Alternative WP34S flashing using Arduino - emece67 - 12-07-2015 06:05 PM

I've been asking myself why such "unexpected" method to flash an wp34s gets so many positive comments. Specially existing some other, cheaper, devices better suited to this task than an Arduino board. A USB to RS232 converter working at 3V3, as in the image, can be get from TAS for less than $2.

[Image: G030.jpg]

I suspect that the culprit is that this method is accompanied by full instructions in a single, all encompassing, PDF document. Perhaps people (like me) using other "more standard" ways to flash their wp34s can write such documentation for their systems.

Thanks adamkov for your nice approach.

RE: Alternative WP34S flashing using Arduino - subaffo - 12-08-2015 08:32 AM

The point is, emece67, that Arduino can easily be already available on the desk or in the drawer of a lot of people: it can be quite convenient.

I agree with you that purposely get an Arduino for this would be quite fool, given the alternatives we have.

And... yes, a well documented method is surely a big advantage and help to the many that would like to transform their 20-30b. Not everyone is an electronic wizard and besides the mythical HP cable and the, unfortunately too, now unavailable Harald's boards, the "average wannabe" user's only chance is to wander in the forum trying to imagine how to connect wires, erase etc....

So, ok, I'll get one of the simple USB-TTL interfaces and will try to put notes and photos to share.

(by the way: someone there who used Arduino at 5V TTL levels is around? Ok: the RX from Arduino can easily be dropped to 3V with two resistors 4k7 -10k to ground. But TX at Arduino side still is 5V while HP sends 3V: just put a 1k?!?)


RE: Alternative WP34S flashing using Arduino - pdicamillo - 04-28-2017 10:34 PM

Clearly not a cost-effective solution for everyone, but if you already have an Arduino, or would like one for other uses, it's great. I have an Arduino Nano from arduino.cc, and I believe it has a genuine FTDI chip. Following these directions, my flashes (using MySamBa) have always worked the first time (unless I made a mistake.) That comes after a great deal of frustration with an inexpensive serial adapter from China with a Prolific chip. I didn't add any resistors to reduce the 5V, and had no issues, although that's probably is a good idea.