- #ARDUINO TIMER INTERRUPT CAUSES CODE TO FAIL WITH GPS HOW TO#
- #ARDUINO TIMER INTERRUPT CAUSES CODE TO FAIL WITH GPS CODE#
I'm not saying not to use direct register writing, but just be aware of the trade off of speed vs.
#ARDUINO TIMER INTERRUPT CAUSES CODE TO FAIL WITH GPS CODE#
It would require more porting effort to use the same code on a different platform even within the Arduino compatible range of processors. your code is locked into the specific processor (family, or often specific model). Writing directly to registers is a valid way to speed up your code, but at the cost of code portability (which is one of the benefits of using the specialized Arduino functions). The memory location of the ISR is known as an "Interrupt Vector." So, our processor will jump to the ISR, perform whatever instructions it finds there, and then jump back to the main program to pick up where it left off (restoring any saved variables it might have previously stored). This is normally a jump command to somewhere else in program memory, which is where the ISR resides.
Often, only a single instruction will reside at the interrupt address.
For example, a falling edge on Port D, Pin 2 is the INT0 interrupt, so execution will jump to address 0 x 0002 (see the Reset and Interrupt Vectors table in the ATmega328P datasheet). Which entry in the table it moves to is based on which interrupt triggered. Execution on your main program will stop, any state variables or numbers the processor was working on are saved to memory, and execution jumps to the IVT. Once all three of these conditions are met, the interrupt will trigger. The interrupt condition must be met (e.g., a falling edge on a particular pin).The individual interrupt must be enabled (usually by setting a bit in a particular register associated with that interrupt).Note that global interrupts are enabled by default in Arduino. Global interrupts must be enabled (in AVR, this is accomplished with the sei() function).Note that you generally need three things to happen to have the interrupt trigger: Part of the setup code might be telling the processor that you are open to an external interrupt when Port D, Pin 2 (also known as interrupt source "INT0") experiences a falling edge (logic HIGH to logic LOW). Your program begins executing sequentially from there. Usually, the only instruction there is a jump command to another place in memory (usually 0 x 0034 - the start of your program space). This just happens to be the RESET vector. When you give power to (or reset) your ATmega328P, the very first instruction that's loaded is at program memory address 0x0000. It can be configured to do other things, but being able to load programs over UART is what makes Arduino work so nicely. Bootloader - Optional section of code that runs first on a microcontroller that allows you to send new programs to it through nontraditional means (e.g., over the UART port instead of the ISP port).Program Space - This is where your main program lives.Interrupt Vector Table (IVT) - Tells the processor where to jump to find the interrupt service routine (ISR) for each interrupt source (e.g., Port D, Pin 2 falling edge).
#ARDUINO TIMER INTERRUPT CAUSES CODE TO FAIL WITH GPS HOW TO#
The NMEA_isr.ino example program shows how to use it.īasically, you use NeoSerial everywhere instead of Serial (and NeoSerial1 instead of Serial1, etc.In the ATmega328P, program memory is divided up into three main sections:
I have modified the standard HardwareSerial class into a new class, NeoHWSerial. I'm not sure updating the display really has to block like that, but. This can be required if some part of your system absolutely has to block (e.g., SD write). It is possible to handle the GPS data during the RX character interrupt. The most important thing getting data from Serial1 when it's available.įor not LCD stuff takes too much time to run so I getting outdated data from serial1 or ever lose data Post ALL your code, with code tags, and perhaps someone can help.Īctually source is pretty big, here is issues part NMEAGPS _GPS_ You are spending way too much time updating the LCD. It is a very bad idea to wait within an interrupt, as other interrupts are blocked.
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