From: Keith Packard Date: Sat, 12 Jan 2013 04:59:27 +0000 (-0800) Subject: Document build process X-Git-Url: https://git.gag.com/?a=commitdiff_plain;h=2f824fd8fb6d24a8063c4cdeae0031de6c0b5815;p=hw%2Fmicropeak Document build process Signed-off-by: Keith Packard --- diff --git a/Build b/Build new file mode 100644 index 0000000..0735b3f --- /dev/null +++ b/Build @@ -0,0 +1,130 @@ + Building MicroPeak Boards + Keith Packard + 2013-01-11 + +Here's the process I'm using to build MicroPeak boards. I build 15 +boards at a time. + +1. Apply paste to the boards. + + 1.1 Check the stencil alignment with a board. Somehow, it always + moves. Adjust and reaffix as necessary. The stencil is hinged on + the side of the board containing the ATtiny85 so that the tiny + ATtiny85 pads are the most carefully aligned. + + 1.2 Load a board. + + 1.3 Apply a bead of paste, on the far side of the ATtiny85 CPU. Spread + paste with the blade nearly parallel to the board. Then scrape + clean with the blade perpendicular to the board. + + 1.4 Clean the stencil every few boards to keep it from sticking to the + boards + +2. Load boards + + 2.1 Prep parts for five boards. I group them as they'll be installed + on the board. There are few enough that it's easy to tell where + every part goes. + + 2.2 Load parts on each board. I do them in this order: + + 1. 100k reset capacitor + 2. 470 LED current limiting capacitor + 3. Power switch + 4. CPU + 5. CPU bypass cap + 6. LED + 7. baro bypass cap + 8. baro sensor + 9. 4.7k SPI resistor + +2.3 After five boards are loaded, prep parts for the next five. + +3. Reflow boards + + 3.1 Group boards in a 3x5 array in the middle of the griddle + + 3.2 Preheat to 100C. + + 3.3 Turn off griddle power. Let it sit for 1 minute + + 3.4 Turn power back on and wait for all parts to reflow + + 3.5 Let it sit for 10 seconds after the last part reflows + + 3.6 Turn off power + + 3.7 Let parts cool on the griddle to below 100C + +4. Flash and self-test + + 4.1 Connect pogo-pin fixture to power supply and AVR programmer + + 4.2 Turn on power supply + + 4.3 Insert board, run 'make load' to flash. Note that a previously + flashed board will need 'make load-slow' to handle the 250kHz + clock speed. + + 4.4 Wait for the flashing to complete. Check for a single orange LED + flash which signals self test complete. + +5. Attach battery holders + + 5.1 Flow a small amount of solder onto the center conductor pad so + that it is raised high enough to hit the battery terminal. + + 5.2 Take the metal battery holder cage, align to the circuit board and + clamp the ATtiny85 end in a vise whose jaws are horizontal. This + end has enough board surface on the parts side to allow clamping, + especially if you align the bypass cap inside a gap in the vise + jaws. + + 5.3 Press down on the battery holder so that the exposed terminal + makes firm contact with the PCB pad. Solder in place. + + 5.4 Remove from vise. + + 5.5 With the vise jaws vertical again, place the board in the end of + the vise with the remaining battery holder terminal exposed. + + 5.6 Solder in place. + + 5.7 Load battery into plastic tray, install in battery holder + +6. System test + + 6.1 Power the board on. Make sure the LED blinks once + + 6.2 Insert into barometric testing chamber (35cc syringe) + + 6.3 Move plunger to 10cc mark. Insert plug + + 6.4 Wait for the altimeter to be ready for boost detect + + 6.5 Increase volume from 10cc to 20cc (halving pressure) + + 6.6 Make sure altimeter registers boost detect by blinking + quickly. + + 6.7 Wait 2 seconds, then decrease volume back to 10cc + + 6.8 Wait for altimeter to indicate landing by blinking out + maximum height + + 6.9 Verify that maximum height is approximately 5500m + + 6.10 Turn off power + +7. Package + + 7.1 Cut 1cm x 4cm piece of closed-cell foam + + 7.2 Insert foam into plastic bag + + 7.3 Push foam to bottom of bag with product card + + 7.4 Drop board into bag, move alongside foam + + 7.5 Push air out of bag and seal