# How to package 12 double variables into JSON Object (Packets)
**URL:** https://discourse.processing.org/t/how-to-package-12-double-variables-into-json-object-packets/33592
**Category:** Electronics (Arduino, etc.)
**Created:** [November 18, 2021, 9:23am UTC](https://discourse.processing.org/t/how-to-package-12-double-variables-into-json-object-packets/33592 "2021-11-18T09:23:08Z")
**Posts on this page:** 5
**Page:** 1
### Author:  [@avong](https://discourse.processing.org/u/avong)
#### Post date: [November 18, 2021, 9:23am UTC](https://discourse.processing.org/t/how-to-package-12-double-variables-into-json-object-packets/33592/1 "2021-11-18T09:23:08Z")
\<
I am developing Processing GUI for PID control.
I wish to use JSON to share data between the PC and the control board.
But i am having issue packaging the JSON object.
I need send and receive 12 variable (double).
I was able to package upto 9 doubles variables.
If i add one more (10 variables) the packet get truncated
This is the Error package:
{“KP”:41.1,“KI”:23.1,“KD”:10.1,“FSP1”:1.0,“FSP2”:1.2,“TPSP”:36.3,“FL1”:0.9,“FL2”:1.8,“TMP”:34.1"UPT
Well packaged (maximum of 9 variables)
{“KP”:41.1,“KI”:23.1,“KD”:10.1,“FSP1”:1.0,“FSP2”:1.2,“TPSP”:36.3,“FL1”:0.9,“FL2”:1.8,“TMP”:34.1}␊
//===========================================================================
//This Function Send JSON Payload
//===========================================================================
typedef struct
{
double \_1FLOWsp; //1 Flow setpoint
double \_2FLOWsp; //2 Flow setpoint
double \_TEMPsp; //Temperature setpoint
double \_kp; //This is PID kp set by user
double \_ki; //This is PID ki set by user
double \_kd; //This is PID Kd set by user
double \_1FLmeas; //This flow rate measured from sensor1
double \_2FLmeas; //This flow rate measured from sensor2
double \_TEMPmeas;
double \_PWRmeas; //This is Power consumed by the system unit
double \_1TANKmeas; //This is water level in the upper tank
double \_2TANKmeas; //This is water level in the lower tank
}MPACKET;
void JSONpayload()
{
char PAYLOAD[250];
MPACKET data;
```
data._kp=41.1;
data._ki=23.1;
data._kd=10.1;
data._1FLOWsp=1.0;
data._2FLOWsp=1.2;
data._TEMPsp=36.3;
data._1FLmeas=0.9;
data._2FLmeas=1.8;
data._TEMPmeas=34.1;
data._1TANKmeas=12.1;
data._2TANKmeas=1.1;
data._PWRmeas=21.1;
sprintf(PAYLOAD,
"{\"KP\":%.1f," //KP
"\"KI\":%.1f," //KI
"\"KD\":%.1f," //KD
"\"FSP1\":%.1f," //Flow rate set-point
"\"FSP2\":%.1f," //Flow rate set-point
"\"TPSP\":%.1f," //Temp set-point
"\"FL1\":%.1f," //1 Flow rate measured
"\"FL2\":%.1f," //2 FLow rate measured
"\"TMP\":%.1f" //Temperature measured
"\"UPT\":%.1f" //1 Tank water level
// "\"DWT\":%.1f" //2 Tank water level
// "\"PWR\":%.1f" //Power consumed
"}\n"
,data._kp
,data._ki
,data._kd
,data._1FLOWsp
,data._2FLOWsp
,data._TEMPsp
,data._1FLmeas
,data._2FLmeas
,data._TEMPmeas
,data._1TANKmeas
// ,data._2TANKmeas
// ,data._PWRmeas
);
UART0->STREAM(D_PORT, PAYLOAD);
```
}
/\>
How can i package 12 variables (double) into JSON.
---
### Author:  [@RichardDL](https://discourse.processing.org/u/RichardDL)
#### Post date: [November 18, 2021, 10:26am UTC](https://discourse.processing.org/t/how-to-package-12-double-variables-into-json-object-packets/33592/2 "2021-11-18T10:26:25Z")
Hi @avong, You haven’t said what control board you are using, I’m familiar with Arduino but not others. The code you posted has a sprintf so it has to be the controller code. I like sprintf and used to use it in Arduino. On one project it would not compile, and if you Google ‘arduino sprintf problem’ you’ll find lots.
You could avoid using sprintf by printing the pieces of the json packet using separate print statements. At the receiving end it will look just the same.
---
### Author:  [@avong](https://discourse.processing.org/u/avong)
#### Post date: [November 18, 2021, 10:42am UTC](https://discourse.processing.org/t/how-to-package-12-double-variables-into-json-object-packets/33592/3 "2021-11-18T10:42:36Z")
I am using costumed Atmega328P board, i use eclipse IDE + avr plugin.
The Processing GUI has no issue, i can read once incoming data (JSON format) from the 9 variable i could packet into JSON format.
The challenge is, i can go beyond 9 variables, when i do, i get errors (truncated packet).
I was thinking there is internal buffer declared using char\* pointer which truncates my packet. but when i check i could only see extern int sprintf(char \*\_\_s, const char \*\_\_fmt, …); in stdio.h header.
---
### Author:  [@RichardDL](https://discourse.processing.org/u/RichardDL)
#### Post date: [November 18, 2021, 10:52am UTC](https://discourse.processing.org/t/how-to-package-12-double-variables-into-json-object-packets/33592/4 "2021-11-18T10:52:03Z")
Yes, alright. I started thinking ‘use 2 shorter pieces for the packet’, then thought ‘don’t bother with the packet, just print all the pieces separately and avoid sprintf completely’. There are also articles saying that using the String data type in Arduino is not very good.
---
### Author:  [@avong](https://discourse.processing.org/u/avong)
#### Post date: [November 18, 2021, 10:55am UTC](https://discourse.processing.org/t/how-to-package-12-double-variables-into-json-object-packets/33592/5 "2021-11-18T10:55:40Z")
Okay,
I will take your first recommendation.
I ealier thought of breaking my packet into 2, but was convience to post my challenge in public, maybe someone will have experience that before.