How do I set banks 0-5 to 1.8v on the maix bit?


#1

I found the resistor to change banks 6 and 7 to 1.8 volts, but how do I change banks 0-5 to 1.8 volts?


#2

If you want set bank 0~5, you need set R3/R4 to change 3V3 to 1V8


#3

Thank you for your reply.
R3 and R4 both appear to be populated on my board. Looking at the altium schematic for the maix bit I see that R3 is part of the voltage controller for the 3.3v rail. So I think I understand that instead of connecting a 0 ohm resistor to connect an IO bank to a voltage bank we are instead changing the 3.3v bank into a 1.8v bank.
ok that seems easy enough, but R3 is 680k and R5 is 300k. I can see changing R3 out for a 300k resistor to match R5, but you also mentioned R4. R4 on the 3.3v bank correlates to R6 on the 1.8v bank, but the are both already 150k and the formula (Ra/Rb +1) * 0.6 = 1.8v with ra = 300k and rb staying at 150k.

So I think if I understand correctly just need to change R3 to 300k and that’s it?

The assembly drawing and schematic I’ve been referencing
http://dl.sipeed.com/MAIX/HDK/Maix-Bit_1.09/MAIX%20Bit_1.09(Assembly%20drawing).pdf
http://dl.sipeed.com/MAIX/HDK/Maix-Bit_1.09/Maix-Bit_1.09(Schematic).pdf


#4

yes, you are right


#5

Thank you so much. I will make the adjustment and give it a try