Because a usb->serial converter coupled takes a lot of space, I’ve decided to build a wisp programmer with a build in converter. I used a ft232 for this job. With the jumper on the pcb I can choose between “target powered” and “usb powered”.
The circuit:
The pcb layout:
Silkscreen-bottom pdf: Link
Copper-bottom pdf: Link
Copper-top pdf: Link
Silkscreen-top pdf: Link
Pictures:
Part list:
| R1 | 4k7 0805 |
| R2 | 10k 0805 |
| R3, R9, R10, R12 | 1k 0805 |
| R4, R5, R6, R7, R8, R11 | 47R 0805 |
| C1, C2, C3, C4 | 100n 0805 |
| C6, C7 | 22pF 0805 |
| C8, C9 | 1µF 0805 |
| C10 | 22µF |
| C11 | 100µF |
| D1, D2, D3 | BAT85 |
| D4 | SB140 SMD |
| D5 | 1N4148 |
| IC1 | FT232RL SSOP28DB |
| IC2 | PIC16F648A SO-18W |
| JP1 | 3p JUMPER |
| L1 | INDUCTOR 0603 |
| LED1 | LED 3MM Red |
| LED2 | LED 3MM Green |
| Q1 | 20Mhz kristal |
| Q2 | BC847 SOT23 |
| SV1 | 5P female header |
| X1 | USB MINI connector |
| X2 | 15p male sub-d |
The hex file for the pic can be found here: http://www.voti.nl/wisp648/
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