eternal zealot
Hello, I am currently deisnign a watch which tells time using 2x 6bit binary numbers displayed with 12x 603 leds, using an STM32L031F6P6 and a DS3231MZ rtc, powered by a cr2032 coin cell, and a switch positioned like a watch crowm
Thank you in advance for any fixes on the schematic/pcb
please could someone review my schem
lost falcon
Unused pins such as PA6 and PA7 may be marked as unused and will show an 'X' on the schematic. That'll prevent some of the the ERC errors. Also, add PWR_FLAG to VCC and GND to avoid other types of ERC error
toxic sorrel
Do you not need external oscillators on U1 and U3?
lost falcon
DS3231 (U3) has an internal crystal oscillator
trail juniper
DS3231 (U3) has an internal crystal oscillator
still recommended to add one
lost falcon
still recommended to add one
The DS3231 has no facility to add an external crystal -- check the datasheet!
trail juniper
The DS3231 has no facility to add an external crystal -- check the datasheet!
im talking about the stm32
download cubeIDE it will help allot
eternal zealot
im talking about the stm32
What frequency? Other than that do you think that it is ok, especially the led multiplexinh
eternal zealot
Unused pins such as PA6 and PA7 may be marked as unused and will show an 'X' on ...
How to add PWR_FLAG
toxic sorrel
DS3231 (U3) has an internal crystal oscillator
Yeah figured they probably do have internal oscillators but didn’t know what OP had in mind.
lost falcon
How to add PWR_FLAG
Choose the PWR_FLAG symbol (two of them) connect to VCC and GND
simple matrix
still recommended to add one
you dont need a crystal if you're using an external clock for time keeping
the nets on the matrix don't look right
unless its supposed to be mirrored?
theres definitely no way to output a 6 bit number there regardless
trail juniper
you dont need a crystal if you're using an external clock for time keeping
recommended
most stm32 work fine without a crystal but you should add it
simple matrix
do you know why it's recommended?
trail juniper
no but it is
simple matrix
its to improve the timing of the internal clocks
the worst you get is some frequency and phase noise on the internal oscillators
(frequency spread is often a benefit for EMC too)
trail juniper
idk I do it because it is good practice
dense solar
You dont really need one resistor pr LED here.. a column can share resistor..
I did the same mistake when making electronic yatzy dice and was like.. d-oh! after soldering too many resistors..
eternal zealot
I did the same mistake when making electronic yatzy dice and was like.. d-oh! af...
I found that multiplexing online is that correct, I was not sure about anodes and cathodes sharing a pin, did I get the anodes and cathodes the right way round, thanks
simple matrix
Are you planning on charlieplexing?
trail juniper
I think you also need to do something with BOOT0
eternal zealot
Are you planning on charlieplexing?
Yes
eternal zealot
I think you also need to do something with BOOT0
Should that be connected to the J1 header for stm programmer
Does anyone have experience in stm32 programming if so have I go the programming header correct
eternal zealot
there are 2x ERC errors now
trail juniper
you need power flags on your battery input
trail juniper
there are 2x ERC errors now
on BT1
eternal zealot
im not sure what you mean
eternal zealot
you need power flags on your battery input
could you send an example
trail juniper
could you send an example
place this guy on the output of your battery
eternal zealot
place this guy on the output of your battery
on positive and negative?
trail juniper
on positive and negative?
yes
I would also recomend putting your capacitor and resistor values
eternal zealot
i have
eternal zealot
it does not look like it
look under the R/C name there us a value
trail juniper
on these two lines
dense solar
A battery symbol like that should have power output mode on pins
eternal zealot
All that's left is to find a good connector for programming less than 3mm tall (any recommendations would be appreciated)
