Search found 24 matches

by bmarvo
Thu Dec 14, 2017 7:29 pm
Forum: OpenOCD
Topic: OpenOCD write_image fails
Replies: 0
Views: 302

OpenOCD write_image fails

Hi all I am using OpenOCD with a Flyswatter2. I'm targeting a PXA270 with Micron MT28EW512ABA external NOR flash. I used to have an older Micron part that is for all intents and purposes identical to this new one and everything works fine with that. I can successfully do a flash probe, flash info, a...
by bmarvo
Fri Feb 24, 2012 1:52 pm
Forum: PCB Design Questions
Topic: Question about voltage regulator sizing with LED's
Replies: 1
Views: 632

You have the right idea with the full wave rectifier. You just need to keep in mind the ratings for max forward and reverse voltage as well as the forward voltage drop Vf of the diodes. If the Vf of each diode is .6 then when your track is at 5 volts, you'll actually only be working with 3.8 volts a...
by bmarvo
Thu Dec 02, 2010 12:58 am
Forum: SparkFun Product Questions
Topic: max1555 and Li-Po battery problem
Replies: 11
Views: 2405

Re: max1555 and Li-Po battery problem

The sound is coming from the 180 pF capacitor. Ive mimized the sound by replacing the 100 uF caps with 5 and 10 uF caps. The problem now is that it can't supply near as much current as I originally designed it to. If I have more than one led on at a time on the matrix, it overloads and the battery c...
by bmarvo
Wed Dec 01, 2010 4:32 pm
Forum: SparkFun Product Questions
Topic: max1555 and Li-Po battery problem
Replies: 11
Views: 2405

Re: max1555 and Li-Po battery problem

What I did was cut the trace (I have it laid out on a pcb) connected to c16 removing it from the circuit. Now I can power the circuit with the battery connected to the input of the 3.3v linear regulator. Here I measure 5 mA of current. If I bypass the regulator I see 11 mA of current still drawn. Si...
by bmarvo
Wed Dec 01, 2010 2:47 pm
Forum: SparkFun Product Questions
Topic: max1555 and Li-Po battery problem
Replies: 11
Views: 2405

Re: max1555 and Li-Po battery problem

The cap is still in the circuit when I try the test. Youre suggesting I try it without the cap? you think the cap charging has something to do with it?
by bmarvo
Wed Dec 01, 2010 11:43 am
Forum: SparkFun Product Questions
Topic: max1555 and Li-Po battery problem
Replies: 11
Views: 2405

Re: max1555 and Li-Po battery problem

sure heres the full schematic: http://img256.imageshack.us/img256/6697/schemfull.png as you can see I have an atmega128L, an 8x8 led matrix, a usb to uart bridge, and a small dataflash chip The AVR hasn't been programmed yet so the led matrix doesn't draw any current. The only chips drawing current ...
by bmarvo
Wed Dec 01, 2010 9:28 am
Forum: SparkFun Product Questions
Topic: max1555 and Li-Po battery problem
Replies: 11
Views: 2405

Re: max1555 and Li-Po battery problem

It seems as though it jumps up to over 2 amps for a split second on startup which then seems to cut off the battery. If I measure the current at the input of the 3.3v linear regulator (bypassing the boost stage) it jumps up to about 300 mA then cuts off. Any idea why its doing this? Is there anythin...
by bmarvo
Wed Dec 01, 2010 5:49 am
Forum: SparkFun Product Questions
Topic: max1555 and Li-Po battery problem
Replies: 11
Views: 2405

Re: max1555 and Li-Po battery problem

sorry forgot to mention that the led direction is wrong in the schematic. I have it the correct way in the circuit. The current is calculated
by bmarvo
Tue Nov 30, 2010 10:31 pm
Forum: SparkFun Product Questions
Topic: max1555 and Li-Po battery problem
Replies: 11
Views: 2405

max1555 and Li-Po battery problem

First here's my schematic: http://img222.imageshack.us/img222/21/powersupply.png Its a max1555 powered from usb with the Li-Po battery connected to a two stage regulator. First an mc34063 to boost it to 5v and then a 3.3v linear reg (not a LDO). The battery is: http://www.sparkfun.com/products/339 T...
by bmarvo
Sat Feb 06, 2010 10:07 pm
Forum: PCB Design Questions
Topic: rejected by the DRC bot
Replies: 4
Views: 785

They're holes made using the Hole command in eagle. The fine line circle is the dimension layer, just like the fine line around perimeter.

edit: but to avoid future problems Ill likely take that advice
by bmarvo
Sat Feb 06, 2010 7:20 pm
Forum: PCB Design Questions
Topic: rejected by the DRC bot
Replies: 4
Views: 785

rejected by the DRC bot

The DRC bot failed my board for violating the 8 mil trace width limit. My traces are all greater than 8 mils and the only thing highlighted in the picture I got in the email is a single pixel vertical line down the right edge of the board: http://img5.imageshack.us/img5/2981/topig.png any ideas? The...
by bmarvo
Thu Jan 07, 2010 9:15 am
Forum: SparkFun Site Questions/Comments
Topic: Not a good sign for free day
Replies: 419
Views: 69939

in all fairness... they didn't quite know what to expect. its not like they've done this before

be patient
by bmarvo
Wed Jan 06, 2010 10:43 pm
Forum: PCB Design Questions
Topic: solder paste dispensing
Replies: 11
Views: 2841

no it is helpful. Next time i will consider the jar paste. The only hard thing is getting a stencil. Pololu has a service that makes stencils for you and even though the price is low, its not something I would buy for just one board.
by bmarvo
Wed Jan 06, 2010 2:49 pm
Forum: PCB Design Questions
Topic: solder paste dispensing
Replies: 11
Views: 2841

yeah the needle is quite a bit larger than a hypodermic needle, but not that big. It extrudes the paste in nice small amounts. I will try using a smaller syringe