STM32-UNO(ARMDuino)

For my students I have designed open source easy to use compatible with Arduino UNO board with STM32F103C8T6 chip – STM32-UNO.
Analog inputs on STM32- UNO are +5V tolerant due to passive voltage divider.
Additional UART port.
External ST Link v.2 programmer/debugger easy connected to right mounted connector. One programmer can be used for many boards.
One user red LED .
One user pushbutton.
Micro-USB port.
VBAT connector to STM32 internal RTC.
BOOT jumpers.
Integrated with DC-DC Step-down power chips 1117XX(+5V and +3V3), it can provide highly efficient and stable power for the shields and other modules, especially suitable for those who want to build a product.

Bill of Materials

Nice, thanks for sharing.

Very nice, well done !

One small thing to notice: If you want to use any analog pin (A0-A5) as digital output, the maximum current you can get is 3.3v / 12000 ohm = 0.000275 Amp that is not enough to light an LED. Moreover, the Amp loss through the R11, R13,..,R21 to the GND is 3.3V / 18000 = 0.18 mA but is too low to concern you.

Maybe it is a good idea to use an extra pin header that is directly connected to pins PA0-PA7 (or through small value resistors).

Is the PA12 usb resistor wired properly?

It is pulled down with 4K7… I think that must be pulled up with 1K5….
Is this working?

[Slammer – Sat Feb 10, 2018 2:31 pm] –
It is pulled down with 4K7… I think that must be pulled up with 1K5….
Is this working?

Probably works on his machine, in the same way the Blue Pill works for most people, even though it’s wrong

Also..

Btw.
SeeedStudio used to sell a board very similar to this… I have one. It’s a nice board, but I never use it, as it’s unnecessarily big for real world projects

I use resistive devider to protect STM32 analog pins from 5V input sygnal. All Arduino shields are 5V devices.
Students connect LEDs, usually, to PWM channels to study STM32 timers.
In my real work I use STM32+CPLD+Analog.
I am Quartus-Altium-LabView-C teacher.

Now STM32-UNO PCB is available on https://www.pcbway.com/project/sharepro … O_new.html.

Nice work.

R6 is definitely wrong. Rather than a pull down it should be a pull up, and the correct resistor value is 1k5. Otherwise it may work on some computers and fail on others.
I just replaced the wrong resistors in a couple of bluepills after then would randomly fail half way during sketch uploads.

Shopping List for ARMDuino.

ARMDuino simple impedance meter shield.

Bioimpedance measurement is an emerging tool in the field of biomedical engineering. It consists in studying the passive electrical properties of biological materials to indirectly determine certain physiological aspects. These measurements usually are employed as a method for monitoring physiological variations. This monitoring method presents three main advantages. First, it is a simple technique that can be applied with just two electrode setup. Also it requires low-cost instrumentation and is able to monitoring in real time.
Impedance meter based on the AD5933 IC, The AD5933 IC is designed as a complete system for the impedance measurement. It consists of a 27-bit direct digital synthesis (DDS) sine excitation voltage (Vout) generator, a digital-to-analogue converter (DAC) and a programmable gain amplifier (PGA1) which
determines the Vout amplitude. The receive stage consists of a current-to-voltage converter (CVC), a programmable gain amplifier (PGA2) and a low pass filter. The data processing block consists of a 12-bit analogue-to-digital converter (ADC) and a 1024 point discrete Fourier transform (DFT) engine with a sample windowing unit and a multiply-accumulate unit (MAC). As the result of DFT, the AD5933 gives a complex number; its modulus and argument should be roportional to the magnitude and phase of the measured current through an unknown impedance Zx which – for a constant amplitude of the voltage excitation – will
also be proportional to the admittance of Zx. An I2C interface provides communication with a microcontroller.
The measurement system is equipped with a female goldpin socket for connecting measured objects directly or for an additional analogue frontend board which contains a DC offset canceller , an additional socket for the measured device under test (DUT) and an external CVC with selectable feedback resistors RFB.

I bought a similar board in the past.

SushiBits One STM32F103CB
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