[Arm-netbook] stress! and working with libopencm3, stm32sprog and an STM32F103

[luke.leighton]

well.  there is a particular issue with stm32sprog which has massively
hindered progress over the past few weeks.  it's very simple: when
uploading and running a program using stm32sprog, if it has interrupt
service routines it is guaranteed to crash.  however if you then set
BOOT0 to 0 and do a RESET, the program will work absolutely fine
[assuming it's coded correctly]

this simple little thing has prevented progress over the past couple
of weeks because it has been impossible to distinguish "code
incorrectly written" from "code that crashed due to stm32sprog".

dozens of examples and bits of code that _should_ have worked - DMA,
ADC, DAC, Timers - will and can now all be revisited.

patience, patience...

... anyway i'm currently tracking how to get timers to update from an
external gpio pin, and from there to fire DMA.  it _is_ possible...
just.... requires a huge amount of careful reading and research just
to come up with only 30 lines of code that connect all the dots
together without connecting any of the thousands of other options.

i think... to be absolutely honest, if i had known that the STM32F was
so comprehensive / complex i would have said "sod it" and used a
low-cost FPGA instead.  but, hey, this is kinda hair-raisingly fun....

l.