11
votes
How can I stop digital pins from floating at reboot?
You could in principle set the pin state a little bit earlier, by
plugging your code into the C runtime's initialization sequence. This,
however, will only buy you a few microseconds: the pins will ...
- 44.8k
6
votes
Accepted
How do I prevent Arduino from running on startup?
The Leonardo should wait a couple of seconds after resetting to see if a new sketch arrives.
Power off the board completely (remove the USB cable).
Hold down the Reset button, and keep it held down (...
- 38.8k
6
votes
Accepted
Where in datasheet is the warning about unreliability of reading PINxn?
did somebody come across such case, or I'm the first in the world?
You are not the first. I recently got bitten by the very same issue.
However, unless you are close to an unusually strong radio ...
- 44.8k
6
votes
Accepted
How can I detect which baudrate a virtual COM port is set to?
From looking at the source it appears that on 32u4 based boards Serial includes extra methods to access the settings from the USB host:
see: https://github.com/arduino/ArduinoCore-avr/blob/...
- 2,120
5
votes
Accepted
Which Arduinos have a true serial port?
There seems to be quite a few Arduinos without a 32U4, like:
Uno (you mentioned it already)
Mega (same)
Lilypad Snap
MKR1000
Pro
Pro Mini
Zero
Due
Ethernet
Mini
Nano
MKR Zero
See the list at ...
- 13k
5
votes
Accepted
Arduino Leonardo(Atmega32u4) - Detecting if USB is connected to a computer?
ADDEN of UDADDR is set if the '32U4 has been assigned a USB address by the host and the firmware wants to enable USB connectivity.
UDADDR & _BV(ADDEN)
- 17.7k
5
votes
Accepted
Help with AlphaNumeric array
All of those "A1" "A2" pins have other numbers that go with them. The A1 or A2 is #defined in the core to be some number. You can just use A1 or A2 and it will work.
For example, try this line and ...
- 3,391
5
votes
Generated frequency is not as expected
digitalWrite() takes a few microseconds to execute as well. There is also some overhead around the delayMicroseconds() function.
If you need exactly 500 kHz, you would want to consider using a timer.
...
- 875
4
votes
Accepted
Can Arduino Leonardo use USB port and RX TX serial pins at the same time?
32u4 is multi-serial uC. USB connection works on default serial communication which can be used via Serial.print("somevalue"). On the other hand if you want to use RX/TX on pins 0, 1 which are ...
- 394
4
votes
Arduino I2C Wire.onReceive hangs after a few loops
After a bit of tinkering, I noticed that removing the delay() call in the slave fixed it and there were no more hangs. Also, when using the Servo library to move a servo instead of blinking the led, ...
- 153
4
votes
Accepted
Arduino Leonardo/Pro Micro sleep and USB
The Arduino has several sleep modes. They differ mainly by the clocks
that are kept running, the peripherals that are enabled, and the
possible wake-up sources. All these modes are described in the
...
- 44.8k
3
votes
Library to set internal analog gain of the Arduino?
I would recommend you to check Nick Gammon's example on using the analog comparator by means of configuring the relevant flag bits of registers in the ATmega328. Sample code from the link, by Nick:
...
- 2,114
3
votes
Pressing reset button restarts program only seconds latter
The first thing that happens when you apply power to a board or press reset, is the bootloader executes. That waits for a short time to accept a new sketch over the serial port. If nothing arrives it ...
- 106k
3
votes
How accurate is arduino time keeping?
As others note this is dependent on the oscillator used on the main microcontroller and care needs to be taken to distinguish this from any IC doing the USB communications on boards like the UNO R3. ...
- 131
3
votes
Send Keyboard Media Keys with Keyboard Library
It is indeed possible and also without the requirement to modify the Arduino environment itself. Just register an HID descriptor for the "report ID" for "Consumer Control" (the ...
- 427
3
votes
Multiple SPI device
Some card reaaders (as well as display boards with built-in sd socket) use 10-kOhm resistors in series to the CS, DIN and CLK lines, to perform a cheap 5V to 3.3V level translation. This is really not ...
- 411
3
votes
Accepted
Arduino Leonardo RX TX mystery
An Arduino Leonardo has native USB support. Which means that it has separate serial interfaces to the PC and to the hardware pins.
Serial is only used for the communication with the PC and is ...
- 1,682
3
votes
Accepted
Failed to initialise SD card on Leonardo
A Leonardo has the SPI pins on the ICSP header, not on pins 11, 12, 13.
And a Pro Micro has the SPI pins on 14, 15, 16.
- 1,682
3
votes
Where in datasheet is the warning about unreliability of reading PINxn?
A test with an Arduino Uno.
I used the usb connector to power-on the arduino uno. The led is at PB5, so I have exchanged PB0 and PB5. My test is therefor not the same.
#define LED_PB PB5 // pin ...
- 3,266
3
votes
Multiple Time-Sensitive Tasks
Two possible solutions:
Split the serial string in small pieces so it's (comfortably) less than 50 ms and send the string in 'pieces' … you could even send it until e.g. 45 ms has been reached and ...
- 13k
3
votes
Accepted
Why can the Xbox360 not detect the Arduino Leonardo as keyboard?
Like Juraj and Majenko said. Arduino Keyboard library does emulate "Boot Keyboard".
I use NicoHood HID library and now it works.
- 141
3
votes
Arduino sketch uses too much memory storage space?
There is no problem here, please read the message carefully!
It says you are ONLY using 30% of the available program memory and 19% of the dynamic memory.
You have a LOT more room left.
- 1,045
3
votes
Accepted
LiquidCrystal issue with HD44780 display
The error is, that V0 has VDD level by the way you connected the resistors. The "lower end" of your ladder needs to be at GND, pin 1.
The pin 15 (A) is the anode of the backlight, and is not ...
- 2,303
3
votes
Accepted
Can't type backslash (\) with Keyboard library
You have to keep in mind that the Arduino doesn't send characters to the
computer. Instead, it simulates key presses, and the computer has to
translate those into characters, according to some ...
- 44.8k
2
votes
Accepted
Better cycling through the RGB colors
I think it's worth noting that the three 255 values for RGB colour space is just one way to encode the 255^3 (16,581,375) colours. These include each and every brightness level too.
If you are ...
- 1,139
2
votes
POE with Arduino Leonardo Eth
From the arduino.cc website.
"The optional PoE module is designed to extract power from a conventional twisted pair Category 5 Ethernet cable. PoE module features are as follows: IEEE802.3af ...
- 21
2
votes
Accepted
Trigger countdown with 433MHz transmission
You say The full code includes some differentiation mechanism for all sensors so I'll assume there's some function GetSensorId() that returns 0 to NUM_SENSORS - 1.
So, you need to keep track of a) ...
- 963
2
votes
Library to set internal analog gain of the Arduino?
You seem to be interested mainly in ATSAMD21. There is an application note from Atmel, AT11480: Analog Comparator Application Examples, which may be of interest for you.
From the Getting started ...
- 2,114
2
votes
Send Keyboard Media Keys with Keyboard Library
If you are getting zeros, the most probably cause is it's the library for the IR. Reinstall or update the library. Sometimes you have to reinstall more than one time. That should work.
About media ...
- 21
2
votes
Accepted
Simple Multiple RX/TX SoftwareSerial?
As Ignacio mentions, you should not be stopping and starting the serial ports. Instead just switch between them with .listen():
Enables the selected software serial port to listen. Only one software ...
- 106k
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