Hardware
The XViCO board is based around an STM32F103RCT6, a 64-pin part.
Partial pinout:
1 - VBAT
2 - PC13 - Extruder ENable (R23 = 10k pullup to 3.3V)
3 - PC14 - Extruder DIRection
4 - PC15 - Extruder STEP
5 - PD0 - 8MHz Crystal
6 - PD1 - 8MHz Crystal
7 - NRST - reset button
8 - PC0 - Z STEP
9 - PC1 - Z DIR
10 - PC2 (ADC123_IN12) - Extruder (hotend) Temp (R5 is 4.7k pullup to VDD)
11 - PC3 (ADC123_IN13) - Bed Temp (R14 is 4.7k pullup to VDD)
14 - PA0 - Bed heater MOSFET gate (7R030)
15 - PA1 - Hotend heater MOSFET gate (7R030)
16 - PA2 - Q3 (CA2TF) - "B_FAN" header
17 - PA3 - Q4 (CA2TF) - "E_FAN" header
20 - PA4 (SPI1_NSS) - U38.1?
21 - PA5 (SPI1_SCK) - U38.6?
22 - PA6 (SPI1_MISO) - U38.2?
23 - PA7 (SPI1_MOSI) - U38.5?
24 - PC4 - Z ENable (R22 - 10k pullup to 3.3V)
25 - PC5 - Y STEP
26 - PB0 - Y DIRection
27 - PB1 - Y ENable (R21 - 10k pullup to 3.3V)
28 - PB2 - X STEP
29 I2C SCL
30 I2C SDA
33 - PB12 - X DIR
34 - PB13 - "Level"
35 - SPI2_MISO
36 - SPI2_MOSI
37 - PC6 - X ENable (R20 - 10k pullup to 3.3V)
38 - PC7 - X Home
39 - PC8 - SD pin 3
40 - PC9 - SD pin 2
41 - PA8 - Y Home
42 - PA9 - "TX" on header. Function: USART1TX
43 - PA10 - "RX" on header. Function: USART1RX
44 - PA11 - Z Home switch (also USBDM, but not brought to header)
45 - PA12 - E Home (filament runout?) (also USBDP, but not brought to header)
46 - PA13 - "DO" on header. Function: JTMS-SWDIO
49 - PA14 - "CK" on header. Function: JTCK-SWCLK
50 - PA15 - SD pin 1
51 - PC10 - SD pin 9
52 - PC11 - SD pin 2
53 - PC12 - SD pin 5
54 - PD2 - SD pin 7
61 - PB8 - LCD
Other devices:
L5970D - 12V to 5V Buck regulator
LD1117 - 3.3V Linear regulator
Winbond 25Q64JVS10 - 64Mbit SPI Flash
BUP_5V header - connected to 5V rail and GND
SD pin 4 = GND
SD pin 6 = VCC
Firmware
I desoldered the Winbond flash device and dumped the firmware here. The STM32F103RCT6 firmware is here (many thanks to advice from Samuel Pinches!)I looked for images in the firmware using Irfanview (thanks to this very handy blog entry!) and eventually, this image jumped out:
Well, that's something to go on! After some googling, I landed at another blog, which seemed to explain the situation well.
The logeek.cn site has schematics for an STM32F103-based 3D printer board, it's for a much more sophisticated unit. I suspect the XViCO board is cut down significantly from the original design.
