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/