Accessing Values From Array Within a Library

Projects Programming
1

There are many great examples of how to access information from an array on the net. I ran into a specific case that has me confused. I am using a library for attiny 85 TinyPpmReader.h. This is a simple library that will take PPM signals in from a RC receiver running in pulse position mode and allows you to attach to a pin to process input. Easy enough.

In the code below, I ran into some confusion when trying to access the data in the array. I am trying to filter out a single channel in the ppm stream and print the contents of only 1 channel (Original example prints 8 channels) and eventually map that value to a servo. (I pasted the serial monitor ouput at the end of the code)

I tried accessing the variable stored in the array like this:

void loop()
{
for(uint8_t Idx = 1; Idx <= TinyPpmReader.detectedChannelNb(); Idx++) /* From Channel 1 to Max detected */

if(TinyPpmReader.detectedChannelNb == [5]) //Is this channel 6 in index 0-7?
{
Serial.println(TinyPpmReader.width_us[5); // if so, print only index 5 containing channel 6 values
}
delay(500);
}

Example unedited sketch from library

#include <TinyPinChange.h>
#include <TinyPpmReader.h>
#include <Rcul.h>

#define PPM_INPUT_PIN 2

void setup()
{
Serial.begin(38400);//attiny tx - rx uno does not work at 9600 baud. Set to 38400 @ attiny 1mhz and uno serial console to 38400 baud
TinyPpmReader.attach(PPM_INPUT_PIN); /* Attach TinyPpmReader to PPM_INPUT_PIN pin */
}

void loop()
{

Serial.print(F("* Period="));Serial.print((int)TinyPpmReader.ppmPeriod_us());Serial.println(F(" us "));
Serial.print(F("ChNb="));Serial.println((int)TinyPpmReader.detectedChannelNb());
for(uint8_t Idx = 1; Idx <= TinyPpmReader.detectedChannelNb(); Idx++) / From Channel 1 to Max detected */
{
Serial.print(F("Ch"));Serial.print(Idx);Serial.print(F("="));Serial.print(TinyPpmReader.width_us(Idx));Serial.println(F(" us"));
}

delay(500);
}

This example script prints to the serial console (Uno to attiny85)

Note: There is some formating errors in the output. The original example does not
print the ASCII channel numbers only the char column of the ASCII table.
I have inserted the channel numbers after "ch" below for clarity.

  • Period=17928 us *
    ChNb=8
    Ch=1496 us
    Ch=1744 us
    Ch=896 us
    Ch=1560 us
    Ch=1640 us
    Ch=1496 us
    Cha=1536 us
    Ch=1688 us

Any suggestions? It is probably something simple but I dont think I am googling the correct question to get the correct answer.

2

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3

I tried accessing the variable stored in the array like this:

Why is the 5 in square brackets? Why are you trying to compare [5] to the address of the detectedChannelNb function in the TinyPpmReader class?

if(TinyPpmReader.detectedChannelNb() == 5) //Is this channel 6 in index 0-7?