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Topic: Stackable shields (Read 4 times) previous topic - next topic

Cheater

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i wont copy and paste a 5-page long email thread i've had regarding orders placed with 'em, suffice to say, the prices are good because you're unlikely to ever get the parts.

Heh. I've always gotten my stuff. Sometimes it takes a little while if you order one of their boards (waiting on a 3.3v switching regulator board atm) but the components come fast.

ladyada

#19
Feb 21, 2008, 05:43 am Last Edit: Feb 21, 2008, 05:44 am by ladyada Reason: 1
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Futurlec. :)
Cheap shipping too.

In quantities of 100 the prices are $1.05 and $0.60 respectively.


i wont copy and paste a 5-page long email thread i've had regarding orders placed with 'em, suffice to say, the prices are good because you're unlikely to ever get the parts.

ladyada

#18
Feb 21, 2008, 05:41 am Last Edit: Feb 21, 2008, 05:45 am by ladyada Reason: 1
well, it sounds like a fun & interesting project. let me know when its done & ill check it out!  ill look into integrating it into my designs if its robust

Cheater

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unless you wanted to, say, put -everything- onto another microcontroller. in which case you would try to do the PWM on the attiny2313 and have that controlled via i2c.

Exactly. :)
Makes the library controlling it far simpler and frees up timers.
Was it you who hit a snag with the timers and delay()?
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and the attiny2313 only has 2 timers by the way, whereas the atmega168 has 3, so you'd have to do the PWM in software which means tons of fun debugging that and i2c communication at the same time. especially difficult when the user wants 8-bit PWM is at >20khz!

Well the ATtiny2313 was a example. There are enough different chips to fill any need. ;)

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also, where are you getting an attiny2313 for $1.45 in qty 1? and a 8-pos DIP switch for $0.75 in qty 1? :)

Futurlec. :)
Cheap shipping too.

In quantities of 100 the prices are $1.05 and $0.60 respectively.[/quote]

ladyada

if you look at the schem, most of the motor control pins are for the PWM channels. theres only 3 pins that are used for 'data' - and those are behind a latch - clk, data, enable and latch.
turning into some i2c deal would thus save you a grand total of 2 pins.
unless you wanted to, say, put -everything- onto another microcontroller. in which case you would try to do the PWM on the attiny2313 and have that controlled via i2c. and the attiny2313 only has 2 timers by the way, whereas the atmega168 has 3, so you'd have to do the PWM in software which means tons of fun debugging that and i2c communication at the same time. especially difficult when the user wants 8-bit PWM is at >20khz!

also, where are you getting an attiny2313 for $1.45 in qty 1? and a 8-pos DIP switch for $0.75 in qty 1? :)

+$3 in parts cost -> *at least* +$6 in final cost.  

for example:
$0.40 led + $0.80 PCB + $1.80 chip/passives for i2c = $3 raw cost
$3 * 200% wholesale markup = $6
$6 * 200% retail markup = $12 final cost

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