149 lines
3.2 KiB
Markdown
149 lines
3.2 KiB
Markdown
A Raspberry Pi-compatible PCB that extends the GPIO header with protected I/O, relays, and various features for versatile use in prototyping and project development.
|
|
---
|
|
|
|
# Notes
|
|
|
|
## interface-board issues noticed when soldering
|
|
- [x] digital in TVS diode footprint: dia is larger -> rotate one/space + 1.5mm drill
|
|
- [x] make diodes pwm larger hole
|
|
- [x] make pitch buzzer larger
|
|
-
|
|
|
|
## interface-board issues at first test
|
|
- analog leds vs terminal: CH0 and CH1 swapped (first, second terminal)
|
|
-> renamed nets and added notes
|
|
- analog leds vs terminal: CH2 and CH3 swapped (third fourth terminal)
|
|
-
|
|
- CH1 and CH7 led on
|
|
|
|
|
|
## Power supply board
|
|
FIXME: barrel-connector wrong polarity
|
|
-> change housing (connected via wires)
|
|
-> fix layout, schematic
|
|
|
|
|
|
|
|
# RPI Specs (Zero, 3+)
|
|
- Available (old) Pi: Raspberry Pi 2 Model B v1.1
|
|
- GPIO
|
|
- Low: 0.9V
|
|
- High: 1.6V
|
|
- Input current: 5uA
|
|
- Input capacitance: 5pF
|
|
- Output Current +-17mA
|
|
- Pullup / Pulldown 50-65k
|
|
- EEPROM GPIO0 GPIO1, leave unused
|
|
|
|
|
|
|
|
# Feature Ideas
|
|
- [x] Temperature control
|
|
- fan
|
|
- auto turn on
|
|
- temp sensor
|
|
- ~~turn on via gpio~~
|
|
|
|
|
|
## Supply
|
|
- Input protection
|
|
- [x] TVS
|
|
- [x] reverse polarity (polyfuse will trigger)
|
|
- [x] Fuse (5A polyfuse)
|
|
- [x] buffer
|
|
- [x] Pass through power supply
|
|
- [x] 3.3V, 5V, 12V, 24V Regulator
|
|
|
|
- [x] power by barrel connector (24V 5A)
|
|
- ~~power by usb~~ [not allowed]
|
|
- ~~Switch between power by USB or power supply?~~
|
|
- ~~power by battery~~ [dropped]
|
|
- liion cell connector
|
|
- BMS / charge controller
|
|
- measure battery voltage
|
|
- USB charging port
|
|
|
|
|
|
## IO
|
|
- Input
|
|
- GPIO
|
|
- [x] wide voltage range (-1.7 to 120V)
|
|
- [x] TVS
|
|
- [x] reverse polarity (-1.73V max)
|
|
- [x] Low pass filter
|
|
- [x] Optocoupler input
|
|
- [x] ADC
|
|
- external IC
|
|
- ~~multiplexer?~~
|
|
- protection
|
|
- scale input voltage
|
|
- fixed inputs: 24V 12V 5V 3.3V
|
|
- 20mA input
|
|
- ~~trim potentiometer?~~
|
|
- Output
|
|
- [x] Relay
|
|
- [x] Mosfet
|
|
- [x] Optocoupler output
|
|
- [ ] GPIO with over current protection
|
|
- [ ] GPIO level shift (24V output)
|
|
- [x] PWM pins
|
|
- [x] shift register
|
|
- [ ] DAC
|
|
|
|
- [x] LEDS indicate I/O state
|
|
- [ ] Testpoints
|
|
- [x] ESD protection (tvs diodes uart, i2c...)
|
|
|
|
|
|
## Bus
|
|
- [x] UART/RS485
|
|
- [ ] RS232 Connector
|
|
- [x] I2C Pullup
|
|
- [x] SPI
|
|
- [ ] CAN
|
|
- ~~Serial to usb (if Arduino)~~
|
|
- ~~OWB default GPIO4~~
|
|
|
|
|
|
## UI
|
|
- Input [dropped]
|
|
- Buttons
|
|
- DIP switches?
|
|
- Temperature sensor
|
|
- Encoder
|
|
- Potentiometer
|
|
- Output
|
|
- [ ] Display [RPI display pending]
|
|
- [x] Buzzer
|
|
- [x] LEDS
|
|
|
|
|
|
## Mechanical
|
|
- [x] Barrel plug (24V 3A supply)
|
|
- ~~Screw terminals~~
|
|
- [x] spring loaded?
|
|
- ~~pass through all pins?~~
|
|
|
|
## Housing
|
|
- RPI ports
|
|
- banana sockets for power out
|
|
- screw terminal exposed
|
|
- buttons, leds: need to open up?
|
|
- BNC? []
|
|
|
|
|
|
## Other
|
|
- Extension board with multiplexer
|
|
- Breadboard compatible?
|
|
- SD Card
|
|
- ~~Onboard MCU for standalone use?~~
|
|
- ~~separate bought MCU via i2c for additional GPIO, DAC, ADC in one~~
|
|
|
|
|
|
## Questions
|
|
- what analog input ranges (Voltage, Count)
|
|
- RS232 RS485 SPI, IIC actually necessary? examples
|
|
- CAN to second SPI?
|
|
- 8x shift register outputs, 0.5A open drain or 7mA tristate
|
|
- 2x PWM 30A enough?
|
|
- max used PWM freq? (drop opto if >80khz) |