134 lines
2.5 KiB
Markdown
134 lines
2.5 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.
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**Notes:**
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# Name
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- Pi-multipurpose-Adapter
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- Pi-multi-function-adapter
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- Pi-extension-board
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- universal-Pi-interface-board
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- pi-peripheral-interface
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- raspberry-extension-board
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- Pi-protected-connection-hub
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# RPI Specs (Zero, 3+)
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- Available (old) Pi: Raspberry Pi 2 Modell B v1.1
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- GPIO
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- Low: 0.9V
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- High: 1.6V
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- Input current: 5uA
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- Input capacitance: 5pF
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- Output Current +-17mA
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- Pullup / Pulldown 50-65k
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- EEPROM GPIO0 GPIO1, leave unused
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# Feature Ideas
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## Supply
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- Input protection
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- TVS
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- reverse polarity
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- Fuse
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- buffer
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- Pass through power supply
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- 3.3V, 5V, 12V, 24V Regulator
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- power by barrel connector (24V 3A)
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- power by usb
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- Switch between power by USB or power supply?
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- power by battery
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- liion cell connector
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- BMS / charge controller
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- measure battery voltage
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- USB charging port
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## IO
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- Input
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- GPIO
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- voltage protection
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- 330R, Z
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- wide voltage range 1.6-24V
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- Low pass filter
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- Optocoupler input
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- ADC
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- external IC
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- multiplexer?
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- protection
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- scale input voltage
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- fixed inputs: 24V 12V 5V 3.3V ?
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- trim potentiometer?
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- Output
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- Relay
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- Mosfet
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- Optocoupler output
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- GPIO with over current protection
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- GPIO level shift (24V output)
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- PWM pins
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- shift register
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- DAC
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- LEDS indicate I/O state
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- Testpoints
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- ESD protection
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## Bus
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- UART/RS485
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- RS232 Connector
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- I2C Pullup
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- SPI
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- CAN
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- Serial to usb (if Arduino)
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- OWB default GPIO4
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## UI
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- Input
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- Buttons
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- DIP switches?
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- Temperature sensor
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- Encoder
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- Potentiometer
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- Output
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- Display
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- Buzzer
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- LEDS
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## Mechanical
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- Barrel plug (24V 3A supply)
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- Screw terminals / spring loaded?
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- pin header angled?
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- pin header for extension
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- pass through all pins?
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## Housing
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- RPI ports
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- banana sockets for power out
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- screw terminal exposed
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- buttons, leds: need to open up?
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- BNC? []
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## Other
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- Extension board with multiplexer
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- Breadboard compatible?
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- SD Card
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- Onboard MCU for standalone use?
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- separate bought MCU via i2c for additional GPIO, DAC, ADC in one
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## Questions
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- what analog input ranges (Voltage, Count)
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- RS232 RS485 SPI, IIC actually necessary? examples
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- CAN to second SPI?
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- 8x shift register outputs, 0.5A open drain or 7mA tristate
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- 2x PWM 30A enough?
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- max used PWM freq? (drop opto if >80khz) |