IDB05A1 working without jumper

[raphael declercq]

Posted on April 21, 2017 at 10:17

Hi,

I am using a IDB05A1 board together with a L073RZ, is it normal that the IDB05A1 is working when i remove the J1 jumper?

I don't get why since there's no connection between 3v3 and VDD

Thanks in advance

Raphael

[John F.]

Posted on April 21, 2017 at 11:38

The IDB05A1 is a Bluetooth Low Energy expansion board based on SPBTLE-RF module for STM32 Nucleo.

The L073RZ is an STM32 Nucleo-64 development board with STM32L073RZ MCU, supports Arduino and ST morpho connectivity.

Looking at the schematic for the IDB05A1, J1 is the jumper linking VDD supply for the Bluetooth Low Energy expansion board with the +3V3 supply. However, there are also connections to the microcontroller's PA0 (IRQ), PA7(MOSI), PA6(MISO) and PB3(CLK).

It's likely that the Bluetooth Low Energy expansion board is being powered by parasitically drawing power from PA0, PA7, PA6 and PB3 when they are logic 1 (high). If you set all those pins to Hi-Z or logic 0 (low), the Bluetooth Low Energy expansion board will probably no longer be powered.