Differences

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--- arduino:arduino_on_linux [2017/12/04 01:17] – mithat
+++ arduino:arduino_on_linux [2019/12/29 05:36] – [USBtiny permissions] mithat
@@ Line 1: / Line 1: @@
 ====== Arduino on Linux ======
-Depending on your distribution, you might need to add permission to your user so it can access ''/dev/ttyACM*'' or whatever. On my Debian system, the following worked (as root):
+===== Managing permissions =====
-<code bash>
+==== Serial port permissions ====
+Depending on your distribution, you may need to add permission to your user so it can access ''/dev/ttyACM*'' or whatever. On my Debian sid system, all I needed to do was add my user to the ''dialout'' group. The following did the trick (as root):
+<code>
 # usermod -a -G dialout <username>
 </code>
+==== USBtiny/USBtinyISP permissions ====
+If you plan to use a USBtiny or USBtinyISP to program your Arduino instead of the more conventional approaches, you are likely to encounter a different permission error. On my Debian sid system, I encountered a “Warning: cannot open USB device: Permission denied” error that adding my user to the ''dialout'' group didn't fix.
+I was able to clear it by adding the suggestion at the end of this [[https://learn.adafruit.com/usbtinyisp/avrdude|Adafruit page]]. Specifically, as root create a file ''/etc/udev/rules.d/99-USBtiny.rules'' with the following single line:
+<code>
+SUBSYSTEM=="usb", ATTR{product}=="USBtiny", ATTR{idProduct}=="0c9f", ATTRS{idVendor}=="1781", MODE="0660", GROUP="dialout"
+</code>
+The next time you log in, your programmer //should// work as expected --- unless the ''product'', ''idProduct'', and/or ''idVendor'' attributes aren't as expected. You can confirm their values by plugging in your USBtiny and running ''dmesg'' (as root):
+<code>
+# dmesg
+[404467.789928] usb 2-1.2: New USB device found, idVendor=1781, idProduct=0c9f
+[404467.789930] usb 2-1.2: New USB device strings: Mfr=0, Product=2, SerialNumber=0
+[404467.789931] usb 2-1.2: Product: USBtiny
+</code>
+A USBtinyISP from a different vendor I used identified itself as “USBtinyISP” rather than “USBtiny”, and so the udev rule above didn’t work. The solution was to add an additional rule in a second line to ''/etc/udev/rules.d/99-USBtiny.rules'':
+<code>
+SUBSYSTEM=="usb", ATTR{product}=="USBtiny", ATTR{idProduct}=="0c9f", ATTRS{idVendor}=="1781", MODE="0660", GROUP="dialout"
+SUBSYSTEM=="usb", ATTR{product}=="USBtinyISP", ATTR{idProduct}=="0c9f", ATTRS{idVendor}=="1781", MODE="0660", GROUP="dialout"
+</code>
+Modify as needed for your USBtiny.