ProgArm 0.3

USB / Charging

Buck-Boost Converter switch

On

Off

Reset/Flash Button

Battery port

SPI

Extra (PWM)

I²C

USART

Extra (GPIO and ADC)

SWD

Extra (GPIO-PWM)

VCC

Ring LED

GND

Ring Buttons

Files

v0.3.1-alpha

Photos

Board Photo

Progress

Undecided / Todo / Done

Current stage:

planning -> schematic -> components -> PCB -> waiting for PCBs -> testing

Improvements:

• Use newer and smaller barometer (BMP180? LPS25H?) -- DONE! (Using LPS25H[1] now)
• Smaller bluetooth module with BLE support (CC2541 with BlueBasic or nRF51822 with blessed or nRF8001) -- DONE! (Using nRF8001[2] now)
• Use SMD vibramotor. (But make sure that it does not get stuck)
• Reduce size to fit into 5x5cm (4x7cm currently) to reduce costs. 4x5cm would be great! -- DONE! (4x5cm)
  • Use combined accelgyro and magnetometer (MPU9250[3])
  • Use LPS4012-222L or LPS4018-222L instead of huge inductors. -- DONE! (L-07C15NKV6T and LQM18FN100M00D)
  • Smaller transistors -- DONE! (SOT-723-3)
  • 0402
• Charge LED is disabled when the device is turned off. This leads to false assumption that charging is not working when device is turned off by hardware switch.
• Do not use rare components!
  • Use bq24297[4] with LM3668[5] instead of LTC3566.
  • bq27410[6] instead of LTC2942.
• Optional battery thermistor
• RTC supercap
• No "mode switch"?
• Less ports, more pin headers! -- DONE! (1.27mm pin headers)
• Minimalistic voltmeter. (as ProgArm extension)
• Pulse oximetry (NJL5501R? TCRT1000? Si1142?) -- DONE! (Using Si1142[7] now)
• IR sensor and transmitter system. (as Ring)

Testing

• STM32
• LM3668
• bq27410
• bq24297
• nRF8001 - works, but is not configured yet
• LPS25H
• MPU9250
• Si1142
• Supercap
• Vibration

TODO in 0.3.1

• Route nRF8001 ACTIVE signal.
• Increase reset button threshold (it is too hard to reset the device without going into flashing mode).
• WARNING! Current leakage through STM pin protection diodes when powered off. This causes standby I2C voltage drop and incorrect current measurement by charger chip. Issues need to be solved as current ProgArm 3 is unsafe to operate! Temporary solution: to cut the trace that connects R-ilim to STM32 pin.
• USB circuit has to have a switchable 1k5 pullup ressistor on D+ line added in order to be properly detected by PC.

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