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ressas
Joined: 15 Nov 2019
Posts: 135
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| MPR121 For Proximity |
 Posted: Tue Apr 07, 2020 12:25 am |
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Hello everyone
I have been trying to detect proximity with the mpr121 module for a long time.
I finally succeeded. You can see the code below.
And I got the code from here and adapted it:
http://www.ccsinfo.com/forum/viewtopic.php?t=52320&highlight=mpr121
So thank you to sshahryiar.
But I realized that I could not operate the sensor steadily.
The value I measure changes on its own after a while.
Is there a deficiency in my code?
I think the sensor is of good quality and should work stable.
Thank you for your help
MPR121.h
| Code: |
#define MPR121addr 0x5A
#define Write_MPR121 0xB4
#define Read_MPR121 0xB5
#define ELE_L 0x00 //d
#define ELE_H 0x01 //d
#define OOR_STATU 0x02
#define ELEPROX 0x03
#define ELE0_L 0x04
#define ELE0_H 0x05
#define ELE1_L 0x06
#define ELE1_H 0x07
#define ELE2_L 0x08
#define ELE2_H 0x09
#define ELE3_L 0x0A
#define ELE3_H 0x0B
#define ELE4_L 0x0C
#define ELE4_H 0x0D
#define ELE5_L 0x0E
#define ELE5_H 0x0F
#define ELE6_L 0x10
#define ELE6_H 0x11
#define ELE7_L 0x12
#define ELE7_H 0x13
#define ELE8_L 0x14
#define ELE8_H 0x15
#define ELE9_L 0x16
#define ELE9_H 0x17
#define ELE10_L 0x18
#define ELE10_H 0x19
#define ELE11_L 0x1A
#define ELE11_H 0x1B
#define EFDPROX_L 0x1C //denendi calisti.
#define EFDPROX_H 0x1D //denendi
#define E0BV 0x1E
#define E1BV 0x1F
#define E2BV 0x20
#define E3BV 0x21
#define E4BV 0x22
#define E5BV 0x23
#define E6BV 0x24
#define E7BV 0x25
#define E8BV 0x26
#define E9BV 0x27
#define E10BV 0x28
#define E11BV 0x29
#define EPROXBV 0x2A // deneNdi
#define MHD_R 0x2B //
#define NHD_R 0x2C
#define NCL_R 0x2D
#define FDL_R 0x2E
#define MHD_F 0x2F
#define NHD_F 0x30
#define NCL_F 0x31
#define FDL_F 0x32
#define NHD_T 0x33
#define NCL_T 0x34
#define FDL_T 0x35
#define MHDPROXR 0x36 //
#define NHDPROXR 0x37
#define NCLPROXR 0x38
#define FDLPROXR 0x39
#define MHDPROXF 0x3A
#define NHDPROXF 0x3B
#define NCLPROXF 0x3C
#define FDLPROXF 0x3D
#define NHDPROXT 0x3E
#define NCLPROXT 0x3F
#define FDLPROXT 0x40
#define ELE0_T 0x41
#define ELE0_R 0x42
#define ELE1_T 0x43
#define ELE1_R 0x44
#define ELE2_T 0x45
#define ELE2_R 0x46
#define ELE3_T 0x47
#define ELE3_R 0x48
#define ELE4_T 0x49
#define ELE4_R 0x4A
#define ELE5_T 0x4B
#define ELE5_R 0x4C
#define ELE6_T 0x4D
#define ELE6_R 0x4E
#define ELE7_T 0x4F
#define ELE7_R 0x50
#define ELE8_T 0x51
#define ELE8_R 0x52
#define ELE9_T 0x53
#define ELE9_R 0x54
#define ELE10_T 0x55
#define ELE10_R 0x56
#define ELE11_T 0x57
#define ELE11_R 0x58
#define EPROXTTH 0x59 //denendi
#define EPROXRTH 0x5A //denendi
#define DEBOUNCE 0x5B
#define FIL_CFG1 0x5C
#define FIL_CFG2 0x5D
#define ELE_CFG 0x5E
#define CDC0 0x5F
#define CDC1 0x60
#define CDC2 0x61
#define CDC3 0x62
#define CDC4 0x63
#define CDC5 0x64
#define CDC6 0x65
#define CDC7 0x66
#define CDC8 0x67
#define CDC9 0x68
#define CDC10 0x69
#define CDC11 0x6A
#define CDCPROX 0x6B
#define CDT0_1 0x6C
#define CDT2_3 0x6D
#define CDT4_5 0x6E
#define CDT6_7 0x6F
#define CDT8_9 0x70
#define CDT10_11 0x71
#define CDTPROX 0x72
#define GPIO_CTRL0 0x73
#define GPIO_CTRL1 0x74
#define GPIO_DATA 0x75
#define GPIO_DIR 0x76
#define GPIO_EN 0x77
#define GPIO_SET 0x78
#define GPIO_CLEAR 0x79
#define GPIO_TOGGLE 0x7A
#define AUTO_CFG0 0x7B
#define AUTO_CFG_CTRL 0x7C
#define AUTO_CFGU 0x7D
#define AUTO_CFGL 0x7E
#define AUTO_CFGT 0x7F
#define SRST 0x80
#define TOU_THRESH 0x0F
#define REL_THRESH 0x09
#define SDA_pin pin_C1
#define SCL_pin pin_C0
#use I2C(MASTER, SDA = SDA_pin, SCL = SCL_pin)
void MPR121_init();
unsigned char MPR121_read(unsigned char address);
void MPR121_write(unsigned char address, unsigned char value);
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MPR121.c
| Code: |
#include "MPR121.h"
void MPR121_init()
{
MPR121_write(GPIO_CTRL0, 0x00); //0x73
MPR121_write(GPIO_CTRL1, 0x00); //0x74
MPR121_write(GPIO_DIR, 0x00); //0x76
MPR121_write(GPIO_EN, 0x00); //0x77
MPR121_write(MHD_R, 0x01); //0x2B
MPR121_write(NHD_R, 0x01); //0x2C //3f li bi dene mesafe artıyomu
MPR121_write(NCL_R, 0x00); //0x2D
MPR121_write(FDL_R, 0x00); //0x2E
MPR121_write(MHD_F, 0x01); //0x2F
MPR121_write(NHD_F, 0x01); //0x30
MPR121_write(NCL_F, 0x7F); //0x31
MPR121_write(FDL_F, 0x09); //0x32
/*
MPR121_write(ELE0_T, TOU_THRESH); //0x41
MPR121_write(ELE0_R, REL_THRESH);
MPR121_write(ELE1_T, TOU_THRESH);
MPR121_write(ELE1_R, REL_THRESH);
MPR121_write(ELE2_T, TOU_THRESH);
MPR121_write(ELE2_R, REL_THRESH);
MPR121_write(ELE3_T, TOU_THRESH);
MPR121_write(ELE3_R, REL_THRESH);
MPR121_write(ELE4_T, TOU_THRESH);
MPR121_write(ELE4_R, REL_THRESH);
MPR121_write(ELE5_T, TOU_THRESH);
MPR121_write(ELE5_R, REL_THRESH);
MPR121_write(ELE6_T, TOU_THRESH);
MPR121_write(ELE6_R, REL_THRESH);
MPR121_write(ELE7_T, TOU_THRESH);
MPR121_write(ELE7_R, REL_THRESH);
MPR121_write(ELE8_T, TOU_THRESH);
MPR121_write(ELE8_R, REL_THRESH);
MPR121_write(ELE9_T, TOU_THRESH);
MPR121_write(ELE9_R, REL_THRESH);
MPR121_write(ELE10_T, TOU_THRESH);
MPR121_write(ELE10_R, REL_THRESH);
MPR121_write(ELE11_T, TOU_THRESH);
MPR121_write(ELE11_R, REL_THRESH); //0x58
*/
MPR121_write(AUTO_CFG0, 0x09);
MPR121_write(AUTO_CFGU, 0xC9); //0x7D
MPR121_write(AUTO_CFGL, 0x82); //0x7E
MPR121_write(AUTO_CFGT,0xb5); //0x7F
//MPR121_write(ELE_CFG, 0x84);
//MPR121_write(ELE_CFG, 0x00);
MPR121_write(ELE_CFG, 0x30); //çalışan //0x5E
//////////////////////////////////////////////////
//
MPR121_write(DEBOUNCE,0x71);
//MPR121_write(FIL_CFG1,0x0f); // ff FIL_CFG1 0x5C //1.3
//Touch Threshold = 0x08, Release Threshold = 0x05. TOUCH>release
MPR121_write(EPROXTTH,0x06); // TOUCH relase dokun bırak 0x59
MPR121_write(EPROXRTH,0x05); // RELEASE 0x5A
}
unsigned int8 MPR121_read(unsigned int8 addr)
{
unsigned int8 value = 0;
I2C_Start();
I2C_Write(Write_MPR121);
I2C_Write(addr);
I2C_Start();
I2C_Write(Read_MPR121);
value = I2C_Read(0);
I2C_Stop();
return value;
}
void MPR121_write(unsigned char addr, unsigned char value)
{
I2C_Start();
I2C_Write(Write_MPR121);
I2C_Write(addr);
I2C_Write(value);
I2C_Stop();
}
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example.c
| Code: |
#include <16f1824.h>
#device ADC=10 // 10 bitlik ADC kullanılacağı belirtiliyor.
#fuses XT,NOWDT,NOPROTECT,NOBROWNOUT,NOLVP,NOPUT,NOWRT,NODEBUG,NOCPD
#fuses INTRC_IO, NOWDT, NOMCLR, BROWNOUT//, PLL
#use delay(internal=32000000)
#use rs232(baud=9600,parity=N,xmit=PIN_a0,rcv=PIN_a1,bits=8)
#use i2c(Master,sda=PIN_c1,scl=PIN_c0,slow=400000,FORCE_HW)
#include "MPR121.c"
void main ( )
{
MPR121_init();
INT16 cap_value=0;
while(true)
{
cap_value = MPR121_read(EFDPROX_L); //çalışan 0x1c
printf("cap_value : %ld \n",cap_value);
}
}
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OUTPUT
| Quote: |
cap_value : 216
cap_value : 217
cap_value : 217
cap_value : 218
cap_value : 218
cap_value : 218
cap_value : 221
cap_value : 220
cap_value : 219
cap_value : 220
cap_value : 220
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You can get the data more smoothly by using filters such as bubble sort.
But for example, while a metal object constantly gives the value 195, after a while there are no changes, it becomes 234.
I am trying to solve this problem
Best regards |
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Ttelmah
Joined: 11 Mar 2010
Posts: 19504
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| Posted: Tue Apr 07, 2020 7:52 am |
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Capacitance measures like this will drift with humidity changes.
The unit has 'self adjustment' for this, controlled by registers 0x2B to 0x40.
You are only setting the first few of these registers, and the values you are
using may well be totally wrong. You need to look at AN3891, which
describes how to set the values in these registers for your hardware. |
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ressas
Joined: 15 Nov 2019
Posts: 135
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| Posted: Tue Apr 07, 2020 9:50 am |
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Thank you Ttelmah.
Yes, I read that application note. I also read the application notes AN3893, AN3889, AN3890, AN3891, AN3893.
Its change due to humidity can be met with understanding.
My question is;
I get the value of 224.
In just a few minutes it gets to 238. The new value I got is 238. However, moisture or object does not change.
There are really a lot of application notes for integrated.
I don't think this is an integrated error. I don't know what I did wrong. |
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Ttelmah
Joined: 11 Mar 2010
Posts: 19504
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| Posted: Tue Apr 07, 2020 10:17 am |
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Moisture will be changing.
Just being absorbed into the structure of the PCB used to make the sensor
or drying out from it (modern PCB's tend to be water washed in manufacture). I use a similar sensor to read fluids in pipes. What is amazing is how much
it does drift. Things quite a long distance from the sensor will affect it. So
surfaces pick up or lose moisture as they heat and cool. The capacitance
does also shift with temperature. So you may simply be seeing the chip
itself warming up...
You have to get the self adjustment tuned to match the behaviour of
your system. |
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ressas
Joined: 15 Nov 2019
Posts: 135
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| Posted: Tue Apr 07, 2020 11:56 am |
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| Which integrated are you using ? |
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Ttelmah
Joined: 11 Mar 2010
Posts: 19504
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| Posted: Tue Apr 07, 2020 1:04 pm |
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I'm using a PIC, with built in capacitance sensing, and my own code
to perform the adjustments. I played with several chips when
prototyping, which is why I know this one... |
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ressas
Joined: 15 Nov 2019
Posts: 135
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| Posted: Tue Apr 07, 2020 11:35 pm |
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Formula used for capacity measurement; C=e*(A/d)
A; electrode surface does not change.
D; The distance between the body and the electrode does not change.
E; the object does not change.
But when the humidity changes, the E value will also change. That's right.
1 unit, 2 units, 3 units can be exchanges.
Idle measurement of my sensor: ex. 225.
Measurement when full: 215.
It can take values such as 216,214,217 when full.
However, it gives 215 for the first few minutes when it is full.
Then it starts to give 230 in 1 2 seconds.
When I measure the null value it shows 240.
I mean, the dielectric coefficient of air is 240 when it is 225.
The object's dielectric coefficient is 230 when it is 215.
(dielectric coefficient or integrated measurement value. you understand)
If the value changes step by step, we can say that it is heating up integrated.
If a few units change, we can say that it is changing humidity.
But I think the problem is somewhere else.
AN3889 page 9:
Autoconfig Control register: here we can choose how to change baseline. I used these settings, but I guess I failed. |
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Ttelmah
Joined: 11 Mar 2010
Posts: 19504
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| Posted: Tue Apr 07, 2020 11:46 pm |
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Yes, as I said the PCB material itself tends to dry as the board heats up,
and pick up moisture when cold. Condensation is happening all the time. |
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ressas
Joined: 15 Nov 2019
Posts: 135
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| Posted: Wed Apr 08, 2020 12:09 am |
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OK. If you say so
What do you recommend hardware? |
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Ttelmah
Joined: 11 Mar 2010
Posts: 19504
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| Posted: Wed Apr 08, 2020 1:29 am |
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Your hardware is potentially fine.
You need to spend the time to actually tune the filtration, so it correctly adjusts
the system as the conditions change. This is the hard part of using
capacitance based systems. I had problems because in manufacture
the boards were being wet washed. Though they were then dried, they
tended to settle over the first few weeks... |
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ressas
Joined: 15 Nov 2019
Posts: 135
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| Posted: Wed Apr 08, 2020 1:43 am |
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Wow. I now fully understand what you mean.
I am sorry, my English is not good.
Thank you. I learned something new  |
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temtronic
Joined: 01 Jul 2010
Posts: 9225
Location: Greensville,Ontario
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| Posted: Wed Apr 08, 2020 5:17 am |
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re:
| Quote: | I had problems because in manufacture
the boards were being wet washed. Though they were then dried, |
The company in Toronto where I bought boards from, late 80s, used kitchen dishwasher to clean and dry the PCBs. Next day he'd test them. Any that didn't function 100%, went back to repair dept.
As the sensor is sensitive to humidity, could you add a local 'humidity sensor' to read local humidity, use the 'number' to adjust 'parameters' on your sensor ? More complicated but perhaps a more stable unit ?? |
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ressas
Joined: 15 Nov 2019
Posts: 135
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| Posted: Wed Apr 08, 2020 6:23 am |
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It is interesting that there are no humidity statements in appnote and datasheets.
What you said is most likely true.
First, I will reread all appnotes.
If it doesn't work, I can add the humidity sensor. I don't have a humidity sensor right now.
Reminding: I don't measure liquid. |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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ressas
Joined: 15 Nov 2019
Posts: 135
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| Posted: Wed Apr 08, 2020 1:25 pm |
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| Quote: |
But they left it out of the 2013 datasheet:
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Yes. I made the search on the 2013 datasheet.
In this case, is the moisture filter disabled in the new version? |
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