I’m planning on attaching a 5.0" TFT display to the raspberry pi of my gopigo, but I’m wondering if it will work power-wise, when connecting the decoder to one of the usb ports on the RPI.
The display with the HDMI decoder will draw 500mA or 370mA at half brightness, according to the info on the decoder, at adafruit.
Will the raspberry pi receive enough power from the gopigo to power this display?
# 5.0" 40-pin 800x480 TFT Display without Touchscreen
# TFP401 HDMI/DVI Decoder to 40-Pin TTL Breakout - Without Touch
Note: I’m not asking if the batteries will last, I can just add a large battery pack, but I’m asking if the RPI can comfortably draw enough power through the gopigo board, without causing power issues.
Any info much appreciated.
Sounds similar usage to this post Connect pixy2 to gopigo
Thank you for your reply.
That indeed seems like a similar situation. Good to hear the RPI3 will provide a combined maximum of 1.2A over the usb ports, that should more then likely be adequate for the display and the usb dongle of the wireless keyboard
I’m probably just going to assume the pi will be able to meet this usb current draw specification, when connected to the gopigo and it’s power source.
Thanks again, will post later on when everything works out.
There is a post before from @Matt that gives the specifics. The GoPiGo3 supply circuit design is very good IMO - enough to drive all four cores (till the heat gets in the way) and some for the USB, camera, and onboard WIFi if my less powerfully spec’d memory serves.
I can’t really seem to find that specific post you’re mentioning, with the specifics. But then again, I seem to be satisfied enough that the current draw will not be a problem. Thanks again for your input
Need @matt to chime in on this thread. The GoPiGo3 schematic shows a 2A fuse on the 5v supply so it would appear that a usb load of 500mA might not allow full bore on a 3B+.
A 500ma load on the 5v rail should be fine. If you are running WiFi, Ethernet, HDMI, four sensors, RPi camera, USB devices, and the RPi CPU is at 100% load, there’s a chance you’ll reach the limit (with the additional 500ma draw), but probably not even then.
The 2A fuse is a PTC fuse that will get hot when it’s over-loaded, and it automatically resets when it cools back down. If the draw on the 5v rail is too high and the PTC fuse trips, it will cause a brown-out condition, which could lead to a corrupted RPi SD card (in which case you would need to re-flash the OS image). The fuse should prevent any permanent damage to hardware.
Although the power requirements of the display should be suitable for the GPG3 to run, from a hookup and software standpoint, Dexter Industries does not provide support for connecting and using the display.
Thank you very much for your reply, Matt.
I’m happy to hear your input on this. As I’m planning to use the display at half-brightness (the default), which is spec’d at 370mA, it seems I should be at low risk of tripping the fuse, and worst case scenario if that happens, shouldn’t be a disaster even then.
Thanks again for your input.
Thanks again too @cyclicalobsessive