Reply
Posts: 2
Registered: ‎10-07-2017

Cannot connect to external Zero Gecko

Hi

I am working on a simple wireless weather sensor using the Zero Gecko and an nrf24.

The code is fully functional on a Zero Gecko kit (EFM32ZG-STK3200) which contains an EFM32ZG222F32.

I designed a pcb with a EFM32ZG110F32 and soldered the components onto it. 

Now I tried using the kit to flash the external board without success ('Could not connect a debugger') based on these instructions: http://community.silabs.com/t5/Simplicity-Studio-and-Software/Using-an-EFM32-Starter-Kit-as-an-exter...

I made sure that the 3.3V is supplied, the board is set to DEBUG OUT (LED is on) and the zg110 is selected in the kit options.

Because I had no idea what could be the cause, I dead-bug-soldered another zg110 to a dip socket in order to test the part on a breadboard. But I still get the same error. 

Based on the reference design and this: http://community.silabs.com/t5/32-bit-MCU/Zero-Gecko-unpacking/td-p/108887 the microcontroller should be programmable without any  additional components. The decoupling caps are not that important and the external oscillators are not needed for this step. Or is it more complicated than that? 

This is the first time I am working with gecko mcus, so do you know what I could be doing wrong?

Posts: 3,142
Registered: ‎02-07-2002

Re: Cannot connect to external Zero Gecko


MaxMKA wrote:

The decoupling caps are not that important [...]


With an attitude like that you will not get far in engineering. I suggest to add proper decoupling and as close as possible to the MCU. Also make sure all power pins are connected.

Posts: 2
Registered: ‎10-07-2017

Re: Cannot connect to external Zero Gecko

Thanks for your answer.

Smiley Happy All necessary decoupling caps are of course included in the pcb, just not in the breadboard circuit at the moment. I never had problems with Atmel chips or PICs chips temporarily running without decoupling caps, but this definitely can lead to unwanted behavior. 

What would a minimal setup/circuit for a gecko mcu look like? Decoupling, ocillators and a pullup for the reset pin? It seems like the external oscillator are not even necessary.

Highlighted
Posts: 3,142
Registered: ‎02-07-2002

Re: Cannot connect to external Zero Gecko

External oscillators are not required. A pullup on reset can be left out. But decoupling is mandatory, I'd say.