VanVince wrote: ↑
Wed Apr 10, 2019 12:30 pm
I already check on the data sheets. The GNSS/GPS/GSM HAT requires 5Volt (operating voltage) in addition the 7 inch display is connected directly to raspberry pi's usb port. The last one, IMU sensor, is connected to the GPIO header (3.3V pin e uart pins).
You also need to look for the current requirements in Amperes, both are required to determine power requirements.
GNSS/GPS/GSM HAT = 5V @ ??A
USB 7 inch display = 5V @ ??A
IMU sensor = 3.3V @ ??A
With those question marks replaced with actual values the total power requirement can be estimated. Tip: if the data sheet has typical current and maximum current given, use the maximum current for the calculation
Because Raspberry Pi compatible 3.3V powered items draw very little power you can ignore the calculation that accommodates the 5V to 3.3V conversion and simply add all the current values together to calculate the total power requirement.
Example calculation using made up values for the unknowns:
Raspberry Pi 3 Model B+ = 500mA typical, 1.3A maximum (2.5 - 1.2)
Reference: https://www.raspberrypi.org/documentati ... /#pi-power
GNSS/GPS/GSM HAT = 350mA = 0.35A
USB 7 inch display = 0.8A
IMU sensor = 10mA = 0.01A
Total current = 1.3 + 0.65 + 0.8 + 0.01 = 2.76A