8 years ago.

how to separate AGND from Gnd?

hello, well my question is that.. i want to separate AGND from gnd, can i do it by hardware or is it by software...

thank you..

Question relating to:

Affordable and flexible platform to ease prototyping using a STM32L053R8T6 microcontroller.

Solder Bridge SB60 links AGND to the Board Ground (0VDC) (ref user Manual schematic)

posted by Martin Simpson 27 Aug 2015

Addition to Martin's post: Look at PDF inside the schematic archive www.st.com/st-web-ui/static/active/en/resource/technical/layouts_and_diagrams/schematic_pack/nucleo_64pins_sch.zip

By the way, separate ground planes is a hardware thing, not software. It is used in PCB design to eliminate (as much as possible) noise propagation through different parts of circuit, especially to protect analog input circuits where weak signal of interest is.

Cheers Miloje

posted by Miloje Zecevic 27 Aug 2015

ok.. thank you guys!

posted by Carlos Josue Cruz Gomez 27 Aug 2015

so you mean that i can just unsolder the fuse on SB60 and thats it?

posted by Carlos Josue Cruz Gomez 27 Aug 2015

You need to connect it somehow. Either to another power supply source or to the original source through a noise filter (a LC filter for example)

posted by Maxime TEISSIER 28 Aug 2015

i have another question, what is the function of the fuse ? i took it off and there is still continuity between AGND and GND but now the adc does not measure well.. any help please!!

posted by Carlos Josue Cruz Gomez 28 Aug 2015

In the old days before A/D converters were integrated into the MCU you would keep the analog ground and digital ground separated from each other and then tie them together at the A/D converter. You will still need to tie the grounds together. However, as one commenter already stated you could experiment with an LC filter between the grounds in an attempt to attenuate digital noise on the analog ground. Managing ground currents in a mixed analog/digital system is both an art and a science. I would recommend looking over some application notes on the topic from the analog masters: TI (try to find the Burr Brown app notes), Analog Devices, Linear Technologies, Maxim.

posted by Doug . 02 Sep 2015
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