HP97 The journey begins

[teenix]

(04-27-2024 10:35 AM)MinkLib Wrote:  I read the CPU_WS.pdf with interest.

The FTDI serial link for reflashing now uses 5v. instead of 3.3v on the Spice board - why is that?
Also why (other than mechanical access) does the board have to be removed to use the serial link?
Can the calculator be powered on (again a la Spice) while serial reflashing?

An exciting new development for sure, for the trusty Woodstock family. Well done indeed, Tony.

The power supply is a little bit different to the Spice. The FTDI powers the CPU board, whereas the Spice does not.

Edit: The battery is difficult to connect with the CPU/Display/Key boards removed from the case so the FTDI board supplies the power.

The 3 possible supplies all with different voltages are isolated from each other, except the battery could override. The display and Bluetooth are powered directly from the battery so while the FTDI is powering the board, or from the programmer which cannot supply enough current to drive a fully operating CPU board, they will not function. There shouldn't be issues with merging supplies, but it was a "just in case' thing.

The serial reflash is just meant as a temporary measure. For external power, the USB cable can be used via the charge connector. You can use the FTDI interface as you would the Bluetooth, to change the menu options or transfer programs via CalCom.

cheers

Tony