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gehakte_bits · (This post was last modified: 12-31-2021 04:40 PM by gehakte_bits.)

‘..Is the hid-usb board powered by the prime or does it require a separated power source?..’

A very good question. The short answer: the FT260 evaluation board and the sensors are currently powered by the Prime through a micro USB<->micro USB cable.

An HP Prime that meets the USB 2.0 specs <should> deliver at least 100mA. Someone Smile

might be able to chime in here (Fuse 1201 'B' ?). All I have as a reference are the open kimono pictures of the wireless kit at https://fccid.io/U6OG0S02/Internal-Photo...to-2149279 and its PID/VID 1915/0101 confirmation of Nordic that leads to https://www.sparkfun.com/datasheets/Wire...%20package. The nRF24LU receiver pulls about 14mA (assuming the RX and TX do not work simultaneously, and the TX pulls only 7.5mA at -12dBm). My guess is the Prime can at least deliver twice that to be reliable (about 25-50mA).

Per the data sheet of the UMFT260EV1, there are various power options. The FT260 takes at the most 25mA, but since the UART/GPIO are suspended in our case, it is probably about 20mA. The FT260 can deliver 100mA, so if you use the FT260 to power your sensor(s) there is about 75mA left (but can the Prime deliver?) It also can provide the 3.3V for many sensors.

As long as you do not plan to run some crazy PWM led drivers to control your Lego Technic motors, you should be ok to connect a low current sensor. I have no problem with the Bosch sensor at 12mA max.

My advice, start with the FT260 only, and then try to read its I2C EEPROM. Then a simple basic I2C sensor, ensure you have the application sheet/programming and pins hookup (The DFR0627 UART spec is all in Chinese, and I had to depend on online translations…I would probably go with a B083D27NJD from waveshare as an alternate). Figure out the power (ground, 5V or 3.3V – keep them separate!) and the I2C Clock and Data lines (4 wires total, incl. power). If you need more power (speakers/LEDs/more common wifi/Bluetooth modem) you might need an external power source.

Enjoy!