PicoStick VGA Information

This is a straightforward PicoMite VGA setup, but is very compact. In spite of its small size (62mm x 31mm) it uses all but one of the GP pins.

It incorpotates:
PS/2 keyboard input
VGA output
Micro SD card socket
Optional RTC. The connector includes pull-up resistors so this can be a general purpose I2C port. (port I2C)
Power input via the PicoMite USB connector or from an external source.
WS2812B LED

GPIO connector H1 includes:
> GP2 - I2C2 SDA, SPI CLK
> GP3 - I2C2 SCL, SPI TX
> GP4 - COM2 TX,  SPI RX
> GP5 - COM2 RX
> 3V3 and GND

GPIO connector H2 includes:
> Three ADC pins.
> Two digital pins.
> Multi-purpose pin can be either VREF or GP0
> 3V3 and GND.


Assembly is a bit fiddly due to the tight spacing, but shouldn't be too difficult if the following guidance is followed:

> Fit the WS2812B first, followed by the Reset button.
> Fit the VGA connector and SD card socket module last.Check all solder joints beneath the SD card holder before soldering it in place as there is no access to them after.Don't push it down so that it shorts onto the connections beneath it!
> Cut the side fixing tabs off the PS/2 socket and solder the casing to the three pads provided, in addition to the usual electrical connections.
> Fit all the components down the centre of the board before fitting the two SIL sockets for the PicoMite.
> Fit the two-pin power supply header and trim its pins down before fitting R3, R5 and D1. R3 and R5 may have to be mounted slightly above the board's surface. That's ok.


Bill Of Materials

1	PCB
1	U1 - Raspberry Pi Pico programmed with PicoMite firmware
1	U2 - WS2812B
1	Micro USB socket module incorporating pull-up resistors and decoupling capacitors (ebay - see pic)
1	Small RTC module - ebay - see pic (Optional)

1	K1 - 90 degree D9F 3-row VGA socket (ebay - see pic)
1	K2 - PS/2 socket (ebay - see pic)
1	H1 - 6-pin female SIP socket
1	H2 - 8-pin female SIP socket
1	H3 - 5-pin male header pins (Optional for RTC module)
1	2-pin male header pins (Optional for external power connector)
2	20-pin female SIP socket for PicoMite

1	C1 - 100nF capacitor. This would probably be better if a tantalum electrolytic of 22uF or so were used.
1	C2 - 100nF ceramic capacitor

1	R1 - 2R2
4	R2, R3, R4, R5 - 10k
2	R6, R9 - 270R
1	R7 - 820R
1	R8 - 390R
2	R10, R11 - 4k7
1	R12 - 1k

1	D1 - 1A Schottky diode
1	D2 - 1N4148 or 1N914
2	Q1, Q2 - VN10KN3-G or BS170. 2N7000 will usually work too.
