More work in progress

[Eric Smith]

Added three more photos.

Richard Ottosen replaced the keyboard and display kludge I hand-wired last month with a DIY-RPN 3 circuit board with only the keyboard, LCD, and LCD power supply stuffed, and wired to a header for a ribbon cable to the EFM32 development kit. There's a mostly 41-like laminated photo paper overlay attached by tape to the keys. This is a huge improvement for development use.

I've made some improvements to the software, mostly to the keyboard scan/debounce, LCD driver, and power management. The LCD contrast can now be adjusted. There's still a lot of work to be done on the software infrastructure, and I should be able to further reduce the power consumption in the light sleep and deep sleep states.

The calculator software has been coming along slowly, though I should be able to make fairly rapid progress now that the infrastructure code has reached the point of being fairly useful.

Edited: 8 Apr 2010, 4:25 p.m.

[Brian Walsh]

Great stuff, Eric! Keep it up!

[hugh steers]

Looks cool.

so what's the EFM32 SDK like? is it stable or new with bits missing. have they supplied useful libraries or is it all writing to the metal :-)

also, which CPU variant are you using - or is this still an option?

good luck!

[Eric Smith]

The supplied libraries are fairly minimal. I'm programming the bare metal, which is generally what I want. I'm currently using the IAR Kickstart package, which can be downloaded at no charge, but only supports executables up to 32KB. IAR does provide a standard C library, but I'm not using much of it. I use printf() for debugging, but it's huge, so I won't use it in the real calculator. I'll most likely be switching the GCC anyhow.

The EVM without the segmented LCD driver uses the EFM32G290F128, which has 128KB of flash and 16KB of RAM. It's in a BGA package, which we don't want to deal with, so when we lay out a PCB it will be for the EFM32G280F128, which is in a 100 TQFP. It has the same memory as the 290 but slightly fewer GPIO pins.

It is expected that there will be new parts with larger memory announced later this year, some of which might be pin-compatible with some of the current parts, which would provide a convenient upgrade path.