Newbie Question about Digital and Analog values

[jeryl.cook]

the below cayenne properties.

#define LPP_DIGITAL_INPUT       0       // 1 byte
#define LPP_DIGITAL_OUTPUT      1       // 1 byte
#define LPP_ANALOG_INPUT        2       // 2 bytes, 0.01 signed
#define LPP_ANALOG_OUTPUT       3       // 2 bytes, 0.01 signed

Does this mean for digital( I/O) the only possible values are 0 and 1.

but for Analog what is the range of possible values?

[shramik_salgaonkar]

that is the data type value in cayenne LPP. read more about it here Cayenne Docs

[jeryl.cook]

Thanks for the link…in the doc…this piece of code for example:

"if ((cursor + LPP_ANALOG_INPUT_SIZE) > maxsize) {
return 0;
}
"

What would be the set maxsize value for analog I/O? …Sorry for basic question I’m just getting requirements for a IoT project.

[shramik_salgaonkar]

you dont have to add anything for this class. you can use TTN cayenne LPP example code which simplifies the coding and can be used with much ease. arduino-device-lib/CayenneLPP.ino at master · TheThingsNetwork/arduino-device-lib · GitHub and add an analog input just by using:
lpp.addAnalogInput(uint8_t channel, float value); where you to add the channel and the analog value reading.

[adam]

@jeryl.cook From the github repository I see #define LPP_ANALOG_INPUT_SIZE 4 // 2 bytes, 0.01 signed and #define LPP_ANALOG_OUTPUT_SIZE 4 // 2 bytes, 0.01 signed Since it’s signed 0.01 that would make the min/max -327.68 to 327.67. If you need larger ranges you can try Energy and Concentration data types. Let me know if that answers your question.

[jeryl.cook]

yes that answers my question!..

I did do a bit of research on why last night it is 2 bytes long, that’s 16 bits. The range of a 16 bit two’s complement number is from -32768 to 32767.

0.01 units to represent a single bit that gives you a range of -327.68 to 327.67. which is your answer! Thanks again.

[jeryl.cook]

@adam

Energy and Concentration data types

I don’t see “Energy and Concentration” data type in the specification?

Type	IPSO	LPP	Hex	Data Size	Data Resolution per bit
Digital Input	3200	0	0	1	1
Digital Output	3201	1	1	1	1
Analog Input	3202	2	2	2	0.01 Signed
Analog Output	3203	3	3	2	0.01 Signed
Illuminance Sensor	3301	101	65	2	1 Lux Unsigned MSB
Presence Sensor	3302	102	66	1	1
Temperature Sensor	3303	103	67	2	0.1 °C Signed MSB
Humidity Sensor	3304	104	68	1	0.5 % Unsigned
Accelerometer	3313	113	71	6	0.001 G Signed MSB per axis
Barometer	3315	115	73	2	0.1 hPa Unsigned MSB
Gyrometer	3334	134	86	6	0.01 °/s Signed MSB per axis
GPS Location	3336	136	88	9	Latitude : 0.0001 ° Signed MSB
Longitude : 0.0001 ° Signed MSB
Altitude : 0.01 meter Signed MSB

[adam]

Looks like it’s not in the github repository yet but it is supported now.

Concentration (ppm) - hex value 0x7D, 3 bytes unsigned
Energy (Wh) - hex value 0x83, 4 bytes unsigned

I can’t promise anything but I’ll take a look at it when I have time and try to make a pull request to add it in.

[jeryl.cook]

Understood. Thank you @adam.
I assume these are the only two new additions to the spec?

[adam]

Yes, just those two. I was talking to one of the cayenne devs and that what they said. You can also manually send that payload if you want, but it’s just not in a convenient package yet.

[jeryl.cook]

one more question lol.

Cayenne Docs

There are quite a few extended datatypes…are there plans to support all of the 'extended IPSO data types" in the dashboard?

[adam]

@eptak Are there any plans to add these extended data types?

[anders.borg]

What scaling should be applied to Concentration and Energy?

Thanks in advance.

[haowong]

Sorry but when I use type ‘0x7D’, the chirpstack tells me the wrong type, is there anything wrong?

[shramik_salgaonkar]

Not sure what you mean by chirpstack tells the wrong type. But in cayenne 0x7D type is not supported. The only datatypes are from the table shared above.