sprintf(tempString, "%04d", thirtySecondTime);
writes 5 characters to tempString, the four digits and a terminating null. You only gave the array room for four.
Serial.println("Timer set to: " + String(tempString));
is a total waste of resources. If you want to talk about memory usage then don't use the String class and definitely ...
I would like to know if they can be connected and, if so, how.
but can we place the shield on the breadboard
No, the pins are misaligned and won't plug in.
and use jumper wire to connect the necessary pins so the Mini can use the WiFi
Yes - connect the jumper wires directly to the WiFi shield pins.
If so, how would we know which pins are ...
This is the standard FTDI Basic connections. CTS is an input to the module and is typically just connected to Gnd as seen on the right side here from the Arduino Promini schematic (so the FT232 is always Clear(ed) To Send, i.e. no flow control is used).
DTR may be broken out on one of the side holes. RTS may work for you in place of DTR to create the reset ...
On the datasheet for the Atmega328P, in the Analog-to-Digital Converter section, is the sentence:
The voltage reference may be externally decoupled at the AREF pin by a capacitor for better noise performance.
The internal voltage reference may thus be decoupled by an external capacitor at the AREF pin to improve noise immunity.
Thus the ...
It's like button, simply connect arduino micro pin to nodeMCU pin and GND of arduino to GND of nodeMCU.
It's also good idea to use two resistors as voltage divider because arduino micro works with 5V and ESP8266 (nodeMCU) with 3V3. 5V can destroy ESP8266 but this thing is still not really clear.
Resistor divider connect as in this link link about ...
can I feed NRF24 directly from Vcc pin?
NO: the pro mini is either 5V or not strong enough to power the RF24.
EDIT: the 3V3 pro mini "could" power the RF24 via VCC, if you use the cap and if it's not the PA&LNA model (or in full power mode). Best practise is to use an external regulator.
if I fed NRF24 directly from battery and reduce 3.7V to 3.3V ...
The CNY70 is just an IR LED and IR Phototransistor. You can treat the IR LED (emitter) portion of it just like any LED and size the resistor appropriately.
The receiver is just a phototransistor which can operate at anything from about 1V up to 32V with no need to adjust anything. The resistor used there is merely a pullup resistor. You can think of the ...
I finally made it work, thx @domen.
I looked at the other part of the schematic and found I was using the wrong pin - I have two LDO and the one I was using was deactivated for sensor.
Thanks all for your help.
To upload a hex file to Arduino over Serial interface, the bootloader must be active. The bootloader is active after reset. It waits a short time if a new application is uploaded. If not, it jumps to existing application.
To reset the MCU on Arduino boards with independent USB chip a circuit connected to DTR line of serial is used.
On a board like the Pro ...
1) Do batteries such as CR123As and Eneloops have built in discharge protection so that they stop supplying power when the voltage is too low?
No, they don't. They just run till there is nothing left.
2) If no, will draining a non-rechargable CR123A be dangerous or problematic in any way? And will draining MiMHs down to 0.85v/0.55v hurt the batteries?
Easy! I like these ProMinis and use them in lots of projects. Simply exchange one of the 12 way header pin strips for a 14 way one (cheap to buy long lengths of these strips from eBay) add small neatly soldered wires to extend A4 and A5 to the extra pins you’ve added and job done.