analogRead(string) fails about remote-wiring

[turkycat]

The analog pins on Arduino and similar devices are numbered after the
digital pins, so "A0" should become 14 on an Arduino uno because there are
14 digital pins numbered 0-13, hence the analog offset. What type of device
are you using?

Jesse

On Sat, Aug 15, 2015, 12:01 PM ManniAT [email protected] wrote:

When I call remDevice.analogRead("A0"); I get an error result.

Debugging the source I found that in Line 132 _analog_offset is added.
For my case this means "A0" - becomes 18
analogRead(18) is called.
And there at line 99 the _analog_offset is added again...

90 uint16_t
91 RemoteDevice::analogRead(
92 uint8_t pin_
93 )
94 {
95 //critical section equivalent to function scope
96 std::lock_guardstd::recursive_mutex lock( _device_mutex );
97

98 uint16_t val = -1;
99 uint8_t analog_pin_num = pin_ + _analog_offset;
100

101 if( _pin_mode[ analog_pin_num ] != static_cast( PinMode::ANALOG ) )
102 {
103 if( _pin_mode[ analog_pin_num ] == static_cast( PinMode::INPUT ) )
104 {
105 pinMode( analog_pin_num, PinMode::ANALOG );
106 }
107 else
108 {
109 return static_cast( val );
110 }
111 }
112

113 if( pin_ <

_num_analog_pins ) 114 { 115 val = analog_pins[ pin ];
116 }
117

118 return val;
119 }
120

121 uint16_t
122 RemoteDevice::analogRead(
123 Platform::String^ analog_pin_
124 )
125 {
126 uint8_t parsed_pin = parsePinFromAnalogString( analog_pin_ );
127 if( parsed_pin == static_cast( -1 ) )
128 {
129 return static_cast( -1 );
130 }
131

132 return analogRead( static_cast( parsed_pin ) + _analog_offset );
133 }
134

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[ManniAT]

Hi Jesse,

I know what you mean - an my Yun A0 is pin 18.
Try to examine the code...

I call analogRead("A0").
In this method parsed_pin becomes correctly 0 - then (on line 132) analogRead is called with parsed_pin + _analog_offset (which is correctly 18 on my yun).
So this results in the call analogRead(18)

At line 99 the _analog_offset is again added.
So _analog_pin_num becomes 36 - FAIL.

[ManniAT]

Just to be more precise - it doesn't matter if the offset is 14 or 18 or whatever.
The offset is added twice this is the problem

[zfields]

HI ManniAT,

As a work around, you can use pin 18 directly on your call to pinMode(18, PinMode::ANALOG), then read it using analogRead(0).
It is confusing, but it reflects the underlying implementation of Firmata, and it will work for you until we get a hot fix out the door. We are glad you're using the library, and thanks for reporting the issue!

[ManniAT]

Hi zfields,

I simply changed line 132 from
return analogRead( static_cast( parsed_pin ) + _analog_offset );
To
return analogRead( static_cast( parsed_pin ) );

And everything works as expected.

[zfields]

Awesome news! Would you like to submit a pull-request? We would love to have your contribution. Either way we should have this fixed by the end of the week, but we would love to give you the opportunity to become a contributor.

[ManniAT]

Ok, I did it.. Request is submitted