[sdiy] REVIEW: Beat707 Arduino Drum Sequencer

[Olivier Gillet]

> Maybe people want to stack their Beat707 board on top of other shields,
> to do something that you haven't thought of yet.

I'll really believe in this "let's stack shields to combine
functionality" mania the day they all run on SPI / I2C / whatever with
DIP-switches on each shield to set its address. At the moment, they
are all using each others' I/O pins. The Beat707 takes all pins except
two digital and one analog, which makes it difficult to add a shield
inbetween :(

> Yeah, but breadboards are a waste of time.  How well do you think 16MHz
> clock oscillators work with 100pF of capacitance between "tracks"?

I've breadboarded a couple of projects with 328p and 644p, all clocked
at 20 MHz, some of them using 10 MHz SPI clocks, and had no problems
with that. However, I have already observed "breadboard bugs" (op-amps
going unstable, unusual noise) on... analog circuits running at audio
frequencies!

> I've got an ICSP cable.  I don't use it, because it's inconvenient and
> no faster than the serial bootloader.  Why bother with it, when I can
> use the serial USB cable I'm already using to send the 32kBytes of code
> in a couple of seconds?

The figures I have just measured, sending the same 28kb blob of code
using avrdude on an ATMega328p are 16s with the standard Arduino
serial bootloader (15.3s of flashing) ; vs 5s with the ISP (2.7s of
flashing). Needless to say that on projects that are making good use
of the larger capacity parts (644p, 1284p, MegaAVR), the flashing time
is a killer... There's a catch, though: off the box, my ISP programmer
was configured to run at 100kHz (probably to deal with the slowest
AVRs running off the internal clock), I had to send a command to it to
set the clock to 1 MHz. This might explain why yours is as slow as the
serial bootloader - or maybe your projects aren't that big.

Olivier