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Need minimalistic example to get STM32 in 48 - pin Package to work.

Oliver R.
Associate III
Posted on November 27, 2017 at 13:47

I can't get a STM32 in 48 - pin Package to work. I need a minimal working reference.

I have a STM32F042K6T6, It works fine, no problems, when I am using it on a breakout board:

0690X00000608xPQAQ.png

Reset pin voltage goes to VDD level, Debugger works, I have a firmware project with Display, External ADC, etc, everything works.

It is LQFP 32. I need more I/O's, so I decided to switch to a 48 pin device.

I picked an STM32L443CCT6 for that, and also because I want the FPU of the M4 and the low power features.

So this is a breakout board I prepared for that:

0690X00000608xUQAQ.png

Problem is: I can't get it up and running.

I tried several times with different types of 64 pin STM32 devices.

The Reset pin voltage stays at VSS level.

I connected it as follows:

pin 7: 100 nF cap to GND (reset pin)

pin 8, 23, 35 and 47: GND

pin 9, 24, 48: VDD = 3V3

pin 44: 10 K resistor to GND (BOOT0 pin)

I also added a 10 uF cap between pin 23 and 24, and two 100nF caps between pins 8/9 and 47/48 (soldered on the bottom side)

Can anyone help ?

Maybe provide a working minimalistic connection exaple for a 48 pin STM32, if possible for the L443CCT6 ?

Maybe the problem is something else, maybe because it is a fresh device and the system clocks are not set correctly ?

Or does anyone know a better breakout board or a minimalistic reference board other than nucleo, i.e. no extra components ?

Or anything else maybe.

BTW I use an ST-link V2 with 4 wire: GND, VDD, SWDIO and SWCLK connected. On the STM32F042K6T6 is works fine, no problems.

I also have nucleo boards with F042K6T6 and L452RET6. None of them, howwever, use a 48 pin device.

#stm32-l4 #lqfp48
16 REPLIES 16
Posted on November 28, 2017 at 11:05

Check all connections directly at the mcu pins. Measure voltage. Add decoupling caps. Measure voltage with an osciloscope. Throw away the breadboard, today.

JW

Posted on November 28, 2017 at 13:59

That would be veeery helpful I guess

Did you use a blank device and were able to attach the debugger (ST-Link V2 I assume) ?

Did you check the behaviour of the reset pin voltage ?

Can you send an image of the board with the F072C ?

Posted on November 28, 2017 at 14:25

And you've confirmed continuity at the IC pins? NRST clamped a zero is indicative of the POR circuit being active.

Board using 49 pin device, same as 48 with a ground pad

https://www.tindie.com/products/TleraCorp/butterfly-stm32l433-development-board/

 
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Posted on November 28, 2017 at 14:56

Clive, soldering MLF in a none-high tech environment is a PITA.

Posted on November 28, 2017 at 14:59

Provided more as a working board/schematic exemplar

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Oliver R.
Associate III
Posted on December 01, 2017 at 13:12

OK, thanky you all for your suggestions. So I will make a PCB with correctly designed decoupling etc.The only way to find out

Posted on December 01, 2017 at 13:07

I can solder QFN housing, but I prefer LQFP because it's a bit easier and this reduces potential problems.