Does DASA programmer need an external clock?

For Adafruit customers who seek help with microcontrollers

Moderators: adafruit_support_bill, adafruit

Please be positive and constructive with your questions and comments.
Locked
lz3060
 
Posts: 9
Joined: Wed Apr 29, 2009 10:43 am

Does DASA programmer need an external clock?

Post by lz3060 »

Hi,

I built a dasa programmer (got the components and built it myself). I am now trying to program an ATMega168 that was on an Arduino (which got upgraded with the 328p). The controller is installed on EvilMad's ATMega Target board, no crystal, just a programming header, power and the microcontroller on it. However, avrdude is not able to communicate to the mcu at all. I thought I've fried the chip, but when I placed it back on the Arduino it worked as if nothing happened.

I checked all electrical connections and verified the voltage levels on all outgoing pins -- all looked good. Voltages varied between -0.6V and 4.7V when toggling the lines, that sounds about right. The CTS line always reads as 0. (Python is great for that kind of stuff, just a few lines in ipython and you have full control over the port!)

Is it because the chip is configured to use an external clock? Or maybe the voltage levels are way out of the spec?

Any advice is appreciated! Thanks :)

mtbf0
 
Posts: 1645
Joined: Sat Nov 10, 2007 12:59 am

Re: Does DASA programmer need an external clock?

Post by mtbf0 »

lz3060 wrote:Is it because the chip is configured to use an external clock?
that would be it.

lz3060
 
Posts: 9
Joined: Wed Apr 29, 2009 10:43 am

Re: Does DASA programmer need an external clock?

Post by lz3060 »

Thanks!

Should I risk connecting my homebrew DASA programmer to the ICSP header on the Arduino and try to set the correct fuses for internal RC clock? Is it possible to damage any of the Arduino peripherals doing this?

mtbf0
 
Posts: 1645
Joined: Sat Nov 10, 2007 12:59 am

Re: Does DASA programmer need an external clock?

Post by mtbf0 »

i'd check to make sure i have all the diodes in right and make sure everything goes to the right place, then i'd check again, then i'd shut my orbs and go for it.

adafruit
 
Posts: 12151
Joined: Thu Apr 06, 2006 4:21 pm

Re: Does DASA programmer need an external clock?

Post by adafruit »

you may have a problem connecting it to an arduino because the SCK pin is connected to an LED which could drive down that pin

mtbf0
 
Posts: 1645
Joined: Sat Nov 10, 2007 12:59 am

Re: Does DASA programmer need an external clock?

Post by mtbf0 »

ladyada wrote:you may have a problem connecting it to an arduino because the SCK pin is connected to an LED which could drive down that pin
if i may be allowed to bring out my ignorance, here, and walk it around a little, what's going on with that? i've programmed a boarduino with a usbtiny and no hassle and programmed all sorts of minipov's with the anode of a single led hanging off of sck, but when i built my cootiecage with 8 leds hooked up through their anodes and another 8 through their cathodes... nothing.

must be that through the resistor and the led and out is an easier way to go than through SCK. is that because SCK is an input and thus in a high impedance state. high impedance, i gather from my readings in charlieplexing, is more or less no place to go, whereas my understanding of english leads me to think of input as a place to go. thus my confusion.

i guess my question becomes if input is no place to go, how's it work?

sorry. just something i had to get off my chest.

adafruit
 
Posts: 12151
Joined: Thu Apr 06, 2006 4:21 pm

Re: Does DASA programmer need an external clock?

Post by adafruit »

leds act like diodes, and the voltage across an LED diode isnt going to be more than maybe 2 or 3 V
each case is different. you can try replacing the 1.5k resistors on the output stage with jumpers (see instructions)

lz3060
 
Posts: 9
Joined: Wed Apr 29, 2009 10:43 am

Re: Does DASA programmer need an external clock?

Post by lz3060 »

Confirmed, it didn't work on the Arduino. I soldered crystal and caps on the target board and it worked there :)

Thanks for the advice!

Locked
Please be positive and constructive with your questions and comments.

Return to “Microcontrollers”