arduino timer interrupt causes code to fail with gps

#ARDUINO TIMER INTERRUPT CAUSES CODE TO FAIL WITH GPS UPDATE#

See String versus char (Step 12)Ħ) Do not use the String + operator at all and avoid using the String(.) constructors as these create short lived temporary Strings. These methods will completely recover all the heap and stack used by their local Strings and other variables on exit. In these methods use local Strings in preference to local char. This says you are trying to modify a const String& arg.ĥ) Do string processing in small compact methods. void strProcessing(const String &input1, const String &input2,, String &result) See Using String& for arguments (Step 11)Ĥ) Set the IDE File → Preferences Compiler Warning to ALL and watch for warning: passing 'const String' as 'this' argument discards qualifiers messages in the compile window.

#ARDUINO TIMER INTERRUPT CAUSES CODE TO FAIL WITH GPS UPDATE#

For results pass a String& result, that the method can update with the result.

Check the return from the last largest reserve( ) to see that you have enough memory for all the StringsĢ) If you have created Strings in the loop() method, they are long lived, move them to Globals and repeat step 1.ģ) Pass all Strings arguments to methods, as const String&. If you have a large sketch, with lots of Strings OR you are concerned about possible memory problems, then following the guidelines below will make your sketch reliable and safe.ġ) Declare long lived Strings as globals and reserve( ) space in setup(), starting with the smallest to the largest. For large sketches OR lots of Strings OR if you think you are having memory problems A future version of Arduino will include fixes for these bugs. Just copy it over the WString.cpp and WString.h in your arduino. This version of WString.cpp and this version of WString.h fixes those bugs. * There are a few obscure bugs in the String library that can crash your sketch otherwise using Strings on AVR boards will not crash/reboot your board. In any case carefully read the Arduino documentation on the String Addition Operator to avoid common coding errors when using the String + operator. Other boards will have more memory available and so you are unlikely to have memory problems using a few Strings. See What happens when UNO runs out of heap memory below (Step 8). If you run out-of-memory, you will just not get all the text in the Strings that you expect. The good news is if you are using an UNO or Mega2560, then using Strings is extremely safe and won't crash your board*, even if you run out-of-memory. Quick Start For small sketches with a few Strings, just use them as convenient.įor small sketches with a few Strings, just use them. As its name suggests, phase and frequency correct PWM allows control over the PWM frequency and it's possible to drive the servos at 50Hz with a 14-bit resolution.Update 9th July 2021 - Added link to fixed versions of Arduino Strings files.

On the Uno timer1 outputs are on digital pins 9 and 10, enough to drive two servos. This means that you can't simultaneousely use libraries that require this timer. Phase and frequency correct PWM uses the 16-bit Timer1. As this hardware PWM isn't interrupt driven it should be unaffected by jitter caused by the GPS. I tried a lot of different ideas, the timer2 was my biggest hope and often mentioned in other forum topics.Ī possible solution is to use the Atmega 328P's phase and frequency correct PWM instead of the servo library. Now it gets loose: It looks like the Adafruit GPS Lib is useing timer1 for UNO boards, therefor I tried to use timer2 Lib for my servo. The arduino UNO has three timers I could use. That interrupt stop's also my PWM signals for the servo, therefore the servo starts to jitter, because it receives random signals. servo Library example: 'sweep' OR servoTimer2 Library example: 'servoTimer2'īoth GPS Libs are using an interrupt to read GPS signals.Adafruit GPS Library example: 'parsing' OR TinyGPSplus-0.94b Library example: 'DeviceExample'.The Servo jitters as soon I pickup GPS data. Unfortunately never a solution which worked with my setup. I know this Problem, using a servo and a GPS sensor, is I guess well known.

Arduino timer interrupt causes code to fail with gps