Atmel AT91SAM7S, ARM7TMDI, OpenOCD and Olimex SAM7-H256 Doc Compilation

A document compilation for a recent purchase of an Olimex SAM7-H256 from SparkFun, an Atmel AT91SAM7S256 based breakout-header dev-board. Includes relevent manuals, datasheets, application notes, and example files from Atmel, ARM, the OpenOCD project, and board descriptions of the Olimex header board.

bzip2 compression was used to decrease file size from 100MB+ to only 35MB.

at91sam7s_docs_all.tar.bz2

Posted by rmrubin Posted in: Programming, Electronics Comments Off December 2007

AVR Synther ADSR Plan B: Success.

Flowcharts are neat. ADSR now works. Gain is exponential on all slopes. Planned adjustments include gain table increase from 256×16 to 1024×16, with a linear ramp mode for the attack mode. 8bit and 16bit output varients planned. Scope image is from a Tektronx 2230 in DSO mode using the Roll mode (as opposed to Scan) for capture of very long waveforms (greater than 3 seconds).

Posted by rmrubin Posted in: Programming, Electronics Comments Off December 2007

VFD Clock Tri-Rail SMPS Milled, Assembled, Working.

VFD clock parts have arrived.

In the interest of saving about 30W of power, a three output switcher supply was chosen for the design instead of a linear regulator setup. Also, the VFD tubes only work with positive grid and anode supplies, so the VFD driver IC will not be able to directly drive the tubes. NPN Darling transistor arrays, P-channel MOSFETs, and a 3 to 8 decoder will be used instead.

The pin sockets soldered directly to the board work perfectly.

Posted by rmrubin Posted in: Electronics Comments Off December 2007

AVR Synther ADSR Gain Envelope. Plan B…

Flowchart for the ADSR gain envelope code, done in Dia.

Posted by rmrubin Posted in: Programming, Electronics Comments Off December 2007

AVR Audio Synthesizer: Freq Done, Volume Done, ADSR Sucks

STK500/ATMega164P/R2R DAC based audio synthesizer. The scope is a Tektronix 2230 Analog/DSO. Tone generation is done using a 1024×8 sample table, DDS phase accumulator and fixed point math. Volume is done with a log gain lookup table adjusted for fixed point multiplication. ADSR sucks at the moment and only functions as very crappy distortion.

Posted by rmrubin Posted in: Electronics Comments Off December 2007

Double Sided Fixture For PCB Milling. It’ll Flip You. Flip You For Real.

Remember? When the cops got Benicio del Toro and he was saying that Stephen Baldwin was going to flip them? No? Anyway…

Having purchased 100 of the same size copper clad FR4 boards, the extra effort was made to machine a proper aluminum fixture for them. 6061 Al is surprisingly cheap at mcmaster-carr. The purpose of said fixture is to hold the board flat on all 4 sides, force distributed over multiple points per side, with an open center area for drilling. References to locate X and Y are integrated into the fixture, Y along the top edge, and X by protruding ‘nubs’ underneath the side clamps. Enough freedom along the X axis is allowed in order to be able to slide the board to the other sides reference after flipping, so the board is always located on the same side, at the same point. Flatness and squareness are critical.

Highlights includes endmills doing circles around broken taps and the taig covered in aluminum chips like it was snow.

Posted by rmrubin Posted in: CNC Comments Off December 2007