PROMPT - Project for Recording, Observing, and Measuring Parachute Tube
The PROMPT is a remote sensor daughterboard that will be placed at the base of the parachute bay, to record metrics regarding the operation of the parachutes. The data from this module will be sent back to the main sensor board over RS485. This includes:
- The pressure of the parachute bay
- The temperature inside the parachute bay
- The temperature in the booster
- Whether or not the payload has been deployed
Temperature Sensing
Since this board needs to monitor 2 remote temperature sensors, choosing a relatively low-cost and compact temperature sensing solution is important. Thermistors are immediately out of the running since the motor's temperature can reach up to 212C, far beyond the range of most NTCs. So, a choice is left between RTDs and Thermocouples. While RTDs would be more accurate, they are more expensive and available in fewer packages than a thermocouple would be.
Component Selection:
0-60PSI pressure: ABP2LANT060PG2A3XX
- Used by Sparkfun
- i2C interface
- Not on JLCPCB
Thermocouple Amplifier: MAX31855
- Used by Adafruit
- 3-Wire SPI interface
- JLCPCB: C52028
RS485 Transceiver: MAX487
- Slew-rate limited
- UART interface
- JLCPCB: C9953
Microcontroller:
- Unknown, probably STM32
Memory: W25Q128JVSIQ
- Same as most other devices on the backplane
- JLCPCB: C97521