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Ai-Thinker-Open / GPRS_C_SDK

Ai-Thinker A9/A9G GPRS (with GPS(A9G)) module C development SDK
https://ai-thinker-open.github.io/GPRS_C_SDK_DOC
MIT License
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New A9G Board Design - Power Supply #532

Open ricardodanielalbano opened 1 year ago

ricardodanielalbano commented 1 year ago

Hello, I'm designing a new board based on A9G module, I'm so confused about power supply for the module and li-ion charging for the battery. I see in the dev board A9G that there isn't carge circuit for the li-ion battery, it's connected directly to a dc-dc step down to 4.2v, also I'm confused if I need to supply 5v to VUSB pin in the A9G module if I'm using VBAT and charging it with the apropiate electronics. Thank you for your help. Regards, RDA.-

Trion commented 1 year ago

You can use tp4056 charger module ouput is 4.2v , A9G module max input voltage is 4.2 v , don't directly connected with 5v to A9G module , VBAT pin max input voltage is 4.2v , VBAT pin is INPUT pin for power supply, not a output pin,

Trion commented 1 year ago

Capture recommended power supply design for A9G module,

Trion commented 1 year ago

https://github.com/Ai-Thinker-Open/GPRS_C_SDK/issues/406

Deenchi1 commented 11 months ago

Hi really need assistance badly. When I power my a9 with ttl converter on the VUSB_PIN ever thing is fine. Once i try to power it at Vbat with 3.7 v 18650 battery or converter the 18650 3.7v to 5v and power it from Vusbi get the same issues. When I send it any AT command I get : jsjskebekks etc. Bunch of jibberish. I tried adding the capacitors stated in above diagram but still nothing please someone anyone help. The baudraute is correct ever works with laptop but not battery.

Deenchi1 commented 11 months ago

Capture recommended power supply design for A9G module,

please help i am unable to power my A9 with 18650 i just attached it to Vbat power for 2s and the A9 gives me back random responses for example: ejdkjdod3okdw

ricardodanielalbano commented 11 months ago

Feeding 4.2v directly to your battery from the switching regulator is not good idea, also in this way the regulator can't do the job was designed for. You need to leave the battery uncoupled from your VBAT net while the switching regulator is working, in the other hand, when no dc input is present in the switching regulator you have to couple the battery again to vbat net, I have implemented this switching circuit in my design, you can check it at #538