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Problem writing to MCP23017 I/O Expander registers (i2c)
I'm going to make the assumption that the cable being tested connects to JP3 and JP4. this means that pins on JP3 will be connected to pins on JP4 when the cable is plugged in to...
Monday, 30 July 2012 - 15:25
Servo troubles (grinding)
Is it only one servo doing this, or all of them? It sounds like something is keeping the servos from moving. Either there's something jammed there, or else the servo is being...
Thursday, 12 July 2012 - 21:16
power switch need help...
You might find this circuit useful: If you connect a GPIO line to the junction of S1 and R5 in...
Friday, 8 June 2012 - 23:30
Help with parallel to serial conversion
The first question that comes to mind is does the data have to be shifted out at 20MHz? If you can get away with Fosc/2 then you could use the SPI port to shift out the data and...
Tuesday, 1 May 2012 - 19:28
UART to UART between 2 uCs
These might be a tad pricey for your circuit, but how about something like this?
Wednesday, 25 April 2012 - 20:12
Creating a 8x8 LED matrix with 2 shift registers?
Your circuit may be designed with a maximum current, but it's not really enforced. LEDs with higher forward voltage drops will leave less voltage across the series resistor, and...
Tuesday, 24 April 2012 - 12:56
Help with 74HC240
A pull-down resistor connected between the interrupt pin and ground should do the job. With an AVR input pin and an 'HC240 output as the only pins on the wire, a 100k resistor...
Friday, 20 April 2012 - 13:46
Creating a 8x8 LED matrix with 2 shift registers?
Those MOSFETs should work just fine, assuming your current stays below 130mA per row. It appears that the Supplier Device Package is what the manufacturer calls the package the...
Wednesday, 18 April 2012 - 14:06
PWM + PoV display, how to determine the sufficient pwm freq?
I discovered the flicker effects of movement by accident. I have a high powered LED headlamp that uses PWM for dimming. I use it for night time hiking, and everything seemed just...
Thursday, 12 April 2012 - 11:56
PWM + PoV display, how to determine the sufficient pwm freq?
If you have a light source that's rapidly moving, it will appear as a bright streak in your view. If the light is flashing, that streak will be broken up into individual segments...
Thursday, 12 April 2012 - 00:48
16*56 Dot matrix soruce and sinking current issues
Your circuit looks fine, as does your code. I don't see anything obviously wrong with either one. The only reason I can think of for the shadow effect would be if your transistors...
Wednesday, 11 April 2012 - 15:31
Simple 1 switch power control/user input
This might be something worth looking at:
Tuesday, 10 April 2012 - 15:23