Arduino pro mini power up

Hi! i want to make an arduino pro mini 3.3V project which has to run as long as possible. I remove the power led and the voltage regulator for power efficient.
My question is if something will happen if i connect it to the computer to upload the sketch because computer's usb voltage is 5V

As long as the external 'things' you did not tell us about are 5V tollerant, then nothing bad.

thanks missdrew for your reply. all external 'things' are 5V tollerant

There is absolutely no difference in the ATmega328 chip between the 3.3 V and 5 V versions of the Pro Mini.

Only two components are ever different - the regulator which you have removed so that is not relevant, and the resonator which is 16 MHz in the 5 V version and 8 MHz in the 3.3 V version as the chip will not run reliably at 16 MHz on 3.3 V.

Obviously the resonators do not care about voltage. :sunglasses:

thanks Paul_B for your reply. you help me a lot. :slightly_smiling_face:

How do you intend to program it..?

It depends on how you power it whilst programming it and also what additional sensors are connected to it.

If all parts of your project can handle 5V, then you can run the whole thing from 5V whilst programming it.

If some parts are 3V3 only, then you need to make sure that your USB adapter can be configured for 3V3 - usually via a jumper on the adapter. Also check that when you have 3V3 selected, that the power pin on the adapter is also outputting 3V3 if you intend to power the board from it whilst programming it.

i tried to program it via ftdi board and i get this error:

avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 1 of 10: not in sync: resp=0xcd
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 2 of 10: not in sync: resp=0xcd
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 3 of 10: not in sync: resp=0xcd
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 4 of 10: not in sync: resp=0xcd
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 5 of 10: not in sync: resp=0xcd
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 6 of 10: not in sync: resp=0xcd
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 7 of 10: not in sync: resp=0xcd
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 8 of 10: not in sync: resp=0xcd
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 9 of 10: not in sync: resp=0xcd
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 10 of 10: not in sync: resp=0xcd
Problem uploading to board. See http://www.arduino.cc/en/Guide/Troubleshooting#upload for suggestions.

Again.....outline exactly how you intend to program it.

Is the FTDI board Vcc 3V or 5V?

I don’t understand what do you mean.

It is 3.3V

If you've got your FTDI board outputting 3V3 on the VCC pin, then you should be able to plug it directly into your Pro Mini. The FTDI board will take care of the 5V on the USB.

Which FTDI board/chip are you using?

I just discovered today on a prototype of mine that the FTDI chip I was using can only supply around 50mA on the 3V3 power pin from its own internal regulator.

Maybe your setup (Inc the bits you've not told us about) takes more than 50mA.

So what? You program the Pro Min at 5 V!

The above statement is open to interpretation.

The external 'things' may run from 3V3 but have 5V tolerant inputs, or they may happily run on a 5V supp!y. Only @Arduinofriend can clarify that.

If they are 3V3 devices, then programming at 5V with them connected does not seem like a wise thing to do.

https://www.youtube.com/watch?v=tKCiNepc6_4

I have had clone prominis that were duds also.
Managed to get around it by programming by usbasp.

The project is a temperature data logger with temperature sensor, sd card module and an rtc. I want to take measure every 15 minutes or so, write data to sd card and then go to sleep mode. The problem now is that it don’t wake up from sleep mode.

Can you provide links to the temperature sensor, SD card module and RTC?

Is your SD card module a barebones board or one designed for a 5V system?

i have a dht22 sensor, rtc ds3231 and sd card breakout board for 5V or 3.3V

Have you seen the web page EXAMPLE USING A RTC TO WAKE-UP AN ARDUINO DATA LOGGER?

A few bullet points from that project:

  • create a data logger that logs temperature/humidity data on an sd card
  • this project will run off a battery pack
  • using the Adafruit DS3231 RTC breakout board
  • use the DHT11/22 sensor to read the temperature and humidity

It sounds exactly like what you are trying to do.