Infrared Proximity Detection with PSoC®
AN50956
Author: Jemmey Huang
Wayne Zhang
Associated Project: Yes
Associated Part Family: CY8C23X33, CY8C24X33
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Software Version: PSoC Designer™ 5.0
Associated Application Notes: None
Application Note Abstract
This application note describes the interface and signal processing for infrared proximity detection using PSoC®. An example
project and a circuit are used to demonstrate the application.
Introduction
Infrared sensors are light sensors, which are active and
function in the infrared part of the frequency spectrum. They
primarily consist of an infrared emitter and an infrared
receiver. They are found in many object detection
applications such as automatic door openers and burglar
alarms, surface feature detection, rotation shaft encoding,
and barcode decoding. Some recently used applications in
mobile devices include auto call-answering, auto speaker
phone activation, and detection of flip-in-clamshell phones.
detector. The reflective sensor can be used in proximity
detection. Some vendors provide a built-in sensor that
includes the receiver and transmitter in a small package. In
this application note, Avago HDSL-9100 is used in the
demonstration circuit.
Figure 2 IR Proximity Sensor Illustration
This application note is bundled with the firmware and
hardware for demonstrating interface and analog signal
processing of infrared proximity sensors using PSoC. It also
explains infrared light sensing and the advantages of using
PSoC in this solution.
Infrared Proximity Sensor
The infrared sensor is made up of the emitter (infrared LED)
and detector (photodiode). The emitter emits IR light pulse
and the receiver detects the corresponding light pulse. The
sensor is classified into transmissive and reflective sensors.
As shown in Figure 1, in a transmissive sensor, the emitter
and the detector face each other. Objects are detected if
they interrupt the beam of light between the emitter and the
detector.
Figure 1 IR Transmissive Sensor Illustration
For a reflective sensor, the emitter and the detector are next
to each other, and are separated by a barrier. Objects are
detected when light is reflected off them and back into the
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Figure 2 is the typical testing circuit for HDSL-9100, which is
an analog-output reflective sensor. It produces a
photocurrent that can be converted to an output voltage
through an external resistor when an object is hit. The light
intensity of the emitter depends on the Vcc to the LED (Pin 1)
and the current limiting resistor (R2).
Typically, the driver from the microcontroller cannot provide
a high current to drive the LED and requires a transistor (Q1)
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to drive the LED at a higher current (possibly higher than
100 mA peak). The infrared intensity of the emitter
influences the detection range. Considering the critical
requirement of the PCB size in mobile phone application,
the demonstration circuit uses two GPIO pins to drive the
LED in parallel and provide current to the emitter.
On the IR receiver side, the desired output voltage depends
on the detection distance and the value of the load resistor
(RLOAD). This output voltage signal can be connected to the
next stage, such as an analog amplifier, comparator, or
Schmitt-Trigger, to control various functions.
The selection of the load resistor, RLOAD, plays a significant
role in circuit operation. If the RLOAD is too large, the RC time
constant increases, thereby increasing the response time.
However, if the RLOAD is too small, it contributes more
thermal noise to the circuit than higher ones. Therefore, it is
important to note the current-to-voltage transfer
characteristics for this part of the circuit. According to the
applications, the RLOAD can be selected in a range of
50 Kohm to several mega ohms. In this demonstration
circuit, we use a 1 Mohm resistor for evaluation.
2.
Interference from other infrared light sources, such as
remote controllers, has the same influence as ambient
light.
3.
Immunity to the power supply system.
4.
Trade-off between detection range and
consumption, especially in portable design.
power
One way to solve these problems is to emit modulated light,
which quickly turns the emitter on and off. The modulated
signal is more reliably detected by a demodulator, which is
tuned to the frequency of the modulated light.
Figure 4 IR Proximity Output under Fluorescent Light
Figure 3 shows the relationship between the obstacle
distance and HDSL-9100 receiver output voltage, under
different energization currents on the HDSL-9100 emitter.
Figure 3 IR Proximity Output versus Distance
With the modulated infrared light, PSoC uses several
implementation methods to handle the signal. These include:
Using external band-pass filter and low-pass filter with
PSoC ADC to sample the filter output. This method
uses external RC network to build the band-pass and
low-pass filter and get the average. The disadvantages
of this method are:
Problems in Infrared Proximity Detection
The following problems in infrared proximity detection
applications need to be solved:
1.
The influence from ambient light, such as sunlight or
fluorescent light. Steady light falling directly on the
detector reduces the sensor's sensitivity. Strong light
can saturate the phototransistor and, in this condition,
the sensor becomes blind. Varying ambient light results
in incorrect signals and non-existent reflection changes.
Therefore, the influence of ambient light must be
minimized by using optical filters, inspired mechanical
design, and, if necessary, using modulation operation.
Figure 4 shows the output signal that the sensor is
under fluorescent light. There is a distinct noise from
the fluorescent, which is 100 Hz frequency with about
70 mv peak-peak amplitude.
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Needs external RC network; consumes more PCB
space.
The passive filter does not have high-Q.
Too much delay if applied to a deep low-pass filter.
Implementation flexibility is not good; the
modulated frequency decides the RC network
value.
Using PSoC internal band-pass filter and low-pass
filter with ADC. This is discussed in the following
section.
Using PSoC internal band-pass filter with synchronous
sampling ADC. A detailed description of this is given in the
section Band-Pass Filter with Synchronous Sampling ADC
on page 3.
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Using PSoC Internal Band-Pass Filter and
Low-Pass Filter
The PSoC flexible on-chip resource provides different
configurable settings that can be used in this application.
The internal SC blocks and CT blocks can be configured as
band-pass filter and low pass filter to process the modulated
signal. The ADC can measure the signal output from the
low-pass filter. Figure 5 shows the block diagram of the
implementation.
In this diagram, a digital block is used to generate a 1.2 KHz
PWM with 50 percent duty. The output drives the IR emitter
through two GPIOs with 100-ohm serial resistors. The IR
receiver output is connected to a PSoC internal band-pass
filter, which is also configured to a 1.2-Khz center frequency.
After the band-pass filter, the signal is routed out through a
pin back to the chip because the chip internal connection
cannot support the signal routing directly to the low pass
filter. A PGA is then used as a buffer to route the signal to a
low-pass filter, in which corner frequency is set at about
500 Hz. The low-pass filter is used as an amplitude
demodulator. Another CT is used as a comparator to detect
the signal polarity from the output of the band-pass filter and
to control the analog modulator in the SC block of the lowpass filter. For more information, refer to AN2044 and
AN2042.
Figure 5 PSoC Design Block Diagram – Using Internal BPF and LPF
P0.1
P0.5
IR Proximity
Sensor
Col.1 Analog
P2.1
P0.4
P0.0
Col. 2/3 Analog
1.2KHz BPF
(2xSC)
PGA
(1xCT)
500Hz LPF
(2xSC)
ADC
Processing
Core
CMP
Col. 3 Analog
100
P1.1
1.2KHz PWM 8bit
(1xDBB)
100
Interrupt
P1.7
PWM Output Control
Figure 6 shows the analog implementation inside PSoC. It
requires a four-column analog block device such as a
diamond chip, and totally consumes two CT blocks and
four SC blocks.
Figure 6 Waveform with BPF & LPF
PSoC output
modulated with the PWM signal. After the processing of
PSoC BPF and LPF circuits, described earlier, the output
signal is showed as the green waveform. It reflects the
average amplitude of the input signal. So it is easy to use
an ADC to sample the signal when PWM is applied to the
emitter, or use a comparator to do an on and off detection.
The obvious disadvantage of this method is that it
consumes too much PSoC resource, although its firmware
is relatively simple. As shown in Figure 7, the configuration
requires four SC blocks and three CT blocks.
Figure 7 PSoC Designer with BPF & LPF
Sensor Signal
This figure shows the signal output from the sensor and
the signal output from PSoC after the processing of
internal band pass filter and low pass filter. The PWM is
applied to the emitter at an interval of 100 ms. The yellow
waveform is the IR receiver output signal, which is
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Figure 9 PWM and Signal Waveform after BPF
Band-Pass Filter with Synchronous
Sampling ADC
Another method for implementing the modulated signal
processing in PSoC is to use a band-pass filter with a
synchronous sampling ADC. The synchronous sampling
ADC exists in some PSoC products like CY8C23x33,
CY8C24x33, and CY8C22x45. The dedicated SAR ADC in
the PSoC is able to work with the PSoC digital block, so
the ADC can be triggered at the point that aligned with the
digital block counter’s value. This function is useful in
many applications like the peak current sampling in the
power conversion application or BEMF signal sampling in
BLDC motor control.
In the configuration, the ADC measures the peak value of
the output of band-pass filter, and then the firmware
calculates the amplitude of the sensor output. Figure 8
shows the signal of the sensor output and the PSoC PWM
output applied on the IR emitter.
Figure 9 shows the signal after the PSoC band-pass filter.
Only the modulated signal is allowed to pass the filter.
Because the delay results from the capacitance load on
the sensor output and the latency from the band-pass filter,
the BPF output signal has some delay or phase shifting
when compared with the PWM signal applied on the
emitter. Different capacitance loads and different bandpass filters result in different phase delays. But, under the
same circuit condition and input signal, the phase delay is
the same. So it is possible to measure the peak value of
the output signal by using the PWM signal to trigger an
ADC at the same delay point. Figure 9 shows the
relationship between the PWM signal and the filter output
signal.
Figure 8 PWM and Sensor Output Waveform
Delay
ADC Sample
PWM
Because the BPF output signal is shifted to analog ground
(AGND), the peak value of the BPF output is higher than
AGND. For an 8-bit ADC, the ADC result of the peak
signal is greater than 0x80.
It is possible to measure the waveform peak and valley
values, and then work out the difference. The amplitude
value of the signal should be twice as sensitive, when
compared with only sampling the peak value. Based on
this conception, we can use the ADC twice in a PWM
period. Figure 10 shows the sampling point of the
waveform. This still uses synchronous sampling ADC as
mentioned before.
Figure 10 Using Double Sampling to Measure Amplitude
1st sample
2nd sample
BPF Output
Amplitude
Sensor
output
ADC
Interrupt
PWM
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PSoC Project
Hardware Block Diagram
This example project demonstrates how to interface and
process the signals from IR proximity sensors with PSoC
on-chip analog and digital blocks and the synchronous
SAR ADC.
is the hardware block diagram of the implementation. In
this circuit, CY8C23533, which has a SAR8 ADC and can
be triggered by the digital blocks, is used as the controller.
The 800 Hz PWM signal drives the LED emitter through
the PSoC GPIO pin. It also triggers the SAR8 ADC at
certain points in every PWM cycle to measure the peak
and valley signal values of the BPF output. The triggering
point of the ADC varies according to the load on the IR
receiver, energization on emitter, and other testing
conditions. With a fixed testing condition, the phase delay
is almost the same. We can measure the delay manually
to decide the ADC trigger point. The LED receiver is
connected to PSoC P2.1 pin and routed to the band-pass
filter directly; no amplifier is required. Use an internal CT
as the buffer to route the BPF output signal to SAR8 ADC
for measurement.
The hardware block diagram of the system is shown in
Figure 11 and the PSoC internal configuration in PSoC
Designer™ is shown in Figure 12 on page 6. The example
project performs the following tasks:
Input
Infrared Proximity sensor.
Processing stage
Driving the emitter of IR proximity sensor with
PSoC PWM signal.
Pre-processing IR proximity output signal by
PSoC band-pass filter.
Converting the band-pass filter output to digital
through a synchronous sampling SAR ADC.
Calculating the amplitude of the band-pass filter
output signal and IR filtering in the firmware.
Providing the amplitude data to host through I2C
interface.
Other types of sensors are also included in the block
diagram as this demonstration board is also used to
demonstrate those sensors.
Output
Providing the amplitude data to host through I2C interface.
Figure 11 System Hardware Block Diagram – Band-pass Filter with Synchronous ADC
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Device Configuration
The analog block layout of the PSoC project is shown in
Figure 12. The PSoC project is built on the demonstration
board using CY8C23533. For a detailed schematic
information, refer to the section Appendix A –
Demonstration Board Schematic on page 9.
Figure 12 PSoC Designer Layout
a CT block can be used as the buffer. Otherwise, route the
signal out to an analog output buffer, and then route it to
port 0 to feed into the ADC. Therefore, the remaining
blocks provide additional functionality to the application.
Application Firmware
The demonstration board samples three types of sensors
in the system and sends out the ADC result through I2C
interface.
CY8C23533 uses the SAR8 ADC to sample the sensors’
output voltage. Among the three sensors, the ambient light
sensor and accelerometer are detected directly without
any pre-condition circuit before going into the ADC input.
The IR proximity detection needs the band-pass filter for
pre-conditioning.
The system has an 800 Hz PWM, which is used to drive
the IR proximity sensor transmitter. Select the 800 Hz
frequency as it is 16 times than that of the 50 Hz power
grid frequency.
Table 1 shows the resource requirements for this
application.
Table 1 Resource Requirements
User Module
requirement
PSoC blocks
required for
each User
Module
User
Module
Flash
User
Module
RAM
SAR ADC(8
bit)
Dedicated analog
PSoC Block
147
0
PWM
1 Digital
Block(DBB)
67
0
Band-Pass
Filter
2 SC Block
109
0
PGA(optional)
1 CT Block
52
0
EzI2Cs
None
264
16
ADC samples the signals with PWM synchronization. This
means the PWM triggers the ADC sample at a specific
point and generates the ADC interrupt after completing
conversion. The firmware responds to the ADC interrupt
and sets up the next trigger point. The sample trigger
points are arranged as shown in Figure 13. Remember
that the PWM is a down-count register, so the firmware
sets the maximum comparison value into the compare
register.
Firmware samples 16 times from different sensor inputs,
and accumulates them. This 16-time sampling period is
about 20 ms, which is the power line cycle. After finishing
the 16-time accumulation, the firmware does an IIR filter
with previous measurement results, and updates the data
to the I2C buffer.
When the band-pass filter starts, there is a delay before
the filter output reaches the expected output value. Every
time the measurement starts, there is a 4-PWM period
delay to start the ADC sampling and result accumulation.
All the testing results, except the IR proximity detection,
are reported in raw data mode. These are the ADC results
after simple IIR filter. For the IR proximity detection, the
result comes from the difference between the peak value
and the valley value. The code is written in C. For detailed
information, refer to Appendix B on page 10.
This application requires one dedicated analog PSoC
block, one digital block, and two SC blocks. If you route
the BPF output to ADC through an internal resource, then
Figure 13 ADC Synchronous Trigger Point with PWM Counter
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Testing of Example Project
Hook up the sensor board with an USBtoIIC bridge.
Open Cypress USBtoIIC GUI.
Click “repeat” and click the “chart” tab. The next
window appears. Check the X, Y, Z, ALS, and IR on
the right window. The IR signal represents the IR
proximity amplitude value measured by PSoC.
Figure 17 IR Proximity Data Showing on USBtoIIC GUI
Set up the variables as shown in Figure 14.
Figure 14 USBtoIIC Variables Setting
Set up the IIC speed to 100Ksps or 50Ksps
Input the command as: r 01 @ver @mode @rate @x
@y @z @aext1 @aext2 @als @alsext1 @alsext2
@IR.
Figure 15 USBtoIIC Command Setting
Moving the finger close to the IR sensor changes the
corresponding curve. Figure 18 shows the obstacle at
a different distance above the sensor. This
experiment uses a Cypress business card as the
obstacle with the test condition: PWM duty – 50
percent, PWM frequency – 800 Hz, and the external
components list as shown in Figure 11 on page 5.
Figure 18 Testing with a Different Distance
Provide 3.3V power supply to the board.
Figure 16 USBtoIIC - Providing 3.3V Power Supply
Summary
This application note describes the interface and signal
®
processing for infrared proximity detection using PSoC .
Modulated infrared proximity detection can be
implemented with the CY8C23x33 device. Its two SC
blocks can be configured as band-pass filters, and the
SAR8 ADC can be triggered synchronously to the internal
PWM used to drive the LED emitter. The system only
consumes two SC blocks and one ADC with very simple
firmware processing.
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Appendix A – Demonstration Board Schematic
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Appendix B – Source Code
Main.C
#pragma interrupt_handler ADC_Int_C();
#pragma interrupt_handler PWM_ISR_C();
void Enable_Accl_Sensor();
char scale(unsigned char data);
#define
#define
#define
#define
#define
#define
#define
TRG_1
TRG_2
TRG_3
TRG_4
TRG_5
TRG_6
TRG_7
195
185
160
130
90
60
30
#include
#include
#include
#include
#include
<m8c.h>
"PSoCAPI.h"
"i2c.h"
"pwm8.h"
"BPF2.h"
unsigned
unsigned
unsigned
unsigned
unsigned
unsigned
char
char
char
char
char
char
// part specific constants and macros
// PSoC API definitions for all User Modules
bPort2_Data = 0;
bPort1_Data = 0;
bADC_cnt = 0;
bPWM_cnt = 0;
bFlag = 0;
bADC_channel = 0;
int result, iResult_H, iResult_L, iResult_ALS, iResult_X, iResult_Y, iResult_Z;
struct FLAG {
unsigned PWM: 1;
unsigned ADC: 1;
unsigned others: 6;
}bIntFlags;
struct SNSData {
unsigned char bX;
unsigned char bY;
unsigned char bZ;
unsigned char bALS;
unsigned char bIR;
} SnsData;
void main()
{
INT i,j;
BYTE bResult;
DWORD dwTemp1;
INT iTemp;
vI2CInit();
I2CSBuff.bMode = 0;
M8C_EnableGInt;
PRT1DR = 0x88;
PGA_Start(PGA_HIGHPOWER);
PWM8_WritePulseWidth(120);
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PWM8_EnableInt();
PWM8_Start();
PWM8_1_Start();
PWM8_2_Start();
BPF2_Start(BPF2_HIGHPOWER);
SAR8_SelectADCChannel(SAR8_ACB01);
SAR8_CONTROL_1_REG = 3; //In auto-triger mode, Low path active
SAR8_TRIGGER_SRC_REG = 1; //set DBB0 as the ADC triger source
SAR8_COMPARE_LO_REG = TRG_6;
SAR8_EnableInt();
SAR8_Start();
while(1)
{
if(bIntFlags.PWM==1) //800HZ PWM interrupt, 1.25ms interval
{
bIntFlags.PWM=0;
bPWM_cnt++;
if(bPWM_cnt==4)//start the ADC after 4 PWM pulse, wait until
{
SAR8_SelectADCChannel(SAR8_ACB01);
//first channel
SAR8_COMPARE_LO_REG = TRG_1;
//first trigger point
bADC_channel = 0;
bADC_cnt = 0;
iResult_H =
iResult_L =
iResult_ALS
iResult_X =
iResult_Y =
iResult_Z =
signal stable
0;
0;
= 0;
0;
0;
0;
SAR8_Start();
}
else if(bPWM_cnt==20) //after 20 pulse count, about 25ms,
{
//output PWM control - disable
if(I2CSBuff.bMode!=0)
//full run mode, every 25ms update 1 time
PRT2GS = PRT2GS & 0x77;
SAR8_Stop();
}
else if(bPWM_cnt>24)
{
if(((I2CSBuff.bMode==1)&&(bPWM_cnt==40))||((I2CSBuff.bMode==2)&&(bPWM_cnt==80)))
{
PRT2GS = PRT2GS | 0x88;
//switch the PWM output to pin
}
}
} // end of if(bIntFlags.PWM==1) //800HZ PWM interrupt, 1.25ms interval
if(bIntFlags.ADC==1) // ADC interrupt
{
switch (bADC_channel)
{
case 0: // dump sample
SAR8_COMPARE_LO_REG = TRG_2;
//DUMP SAMPLE to remove the channel influence
SAR8_SelectADCChannel(SAR8_P0_1);
bADC_channel = 1;
break;
case 1: // sample ALS
SAR8_COMPARE_LO_REG = TRG_3;
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iResult_ALS += SAR8_DATA_LO_REG;
SAR8_SelectADCChannel(SAR8_P0_2);//next channel IR valley
bADC_channel = 2;
break;
case 2: // sample accelerometer sensor - X
SAR8_COMPARE_LO_REG = TRG_4;
iResult_X += SAR8_DATA_LO_REG;
SAR8_SelectADCChannel(SAR8_ACB01);//next channel IR valley
bADC_channel = 3;
break;
case 3: // sample valley value of IR proximity sensor
SAR8_COMPARE_LO_REG = TRG_5;
iResult_L += SAR8_DATA_LO_REG;
SAR8_SelectADCChannel(SAR8_P0_4);//next channel is Y
bADC_channel = 4;
break;
case 4: // sample accelerometer sensor - Y
SAR8_COMPARE_LO_REG = TRG_6;
iResult_Y += SAR8_DATA_LO_REG;
SAR8_SelectADCChannel(SAR8_P0_6);//next channel is Z
bADC_channel = 5;
break;
case 5: // sample accelerometer sensor - Z
SAR8_COMPARE_LO_REG = TRG_7;
iResult_Z += SAR8_DATA_LO_REG;
SAR8_SelectADCChannel(SAR8_ACB01);//next channel is IR peak
bADC_channel = 6;
I2CSBuff.bAcclExt1 = SAR8_DATA_LO_REG;
break;
case 6: // sample peak value of IR proximity sensor
SAR8_COMPARE_LO_REG = TRG_1;
iResult_H += SAR8_DATA_LO_REG;
SAR8_SelectADCChannel(SAR8_P0_1);//next channel is ALS
bADC_channel = 0; // ---bADC_cnt++;
break;
}
if(bADC_cnt==16)
{
if(iResult_H>iResult_L)
result = ((iResult_H-iResult_L)>>4);//+(SnsData.bIR>>1);
else result = 0;
SnsData.bIR = (SnsData.bIR>>1) + (result>>1); //Filter
I2CSBuff.bProxiData = SnsData.bIR;
I2CSBuff.bProxiExt1 = iResult_H>>4;
I2CSBuff.bProxiExt2 = iResult_L>>4;
iResult_H = 0;
iResult_L = 0;
PWM8_1_Stop();
PWM8_1_WritePulseWidth(255-(SnsData.bIR>>1));
PWM8_1_Start();
result = (SnsData.bALS<<1) + SnsData.bALS;
result = result+(iResult_ALS>>4);
SnsData.bALS = result>>2;
I2CSBuff.bAlsData=SnsData.bALS;
iResult_ALS = 0;
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PWM8_2_Stop();
PWM8_2_WritePulseWidth(255-SnsData.bALS);
PWM8_2_Start();
result = (SnsData.bX>>1) + (iResult_X>>5);
SnsData.bX = result;
I2CSBuff.bX=SnsData.bX;
iResult_X = 0;
result = (SnsData.bY>>1) + (iResult_Y>>5);
SnsData.bY = result;
I2CSBuff.bY=SnsData.bY;
iResult_Y = 0;
result = (SnsData.bZ>>1) + (iResult_Z>>5);
SnsData.bZ = result;
I2CSBuff.bZ=SnsData.bZ;
iResult_Z = 0;
bPWM_cnt=0;
bADC_cnt = 0;
}
bIntFlags.ADC = 0;
}//end of if(bIntFlags.ADC==1) // ADC interrupt
}
}
void ADC_Int_C()
{
bIntFlags.ADC = 1;
}
void PWM_ISR_C()
{
bIntFlags.PWM = 1;
}
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I2C.H
About the Authors
#ifndef __I2C_H__
#define __I2C_H__
Name:
#include <m8c.h>
// part specific
constants and macros
#include "PSoCAPI.h"
// PSoC API
definitions for all User Modules
#include "ezi2cs.h"
Title:
typedef struct
{
BYTE bVersion;
BYTE bMode;
BYTE bUpdateRate;
//ACCELEROMETER CONTROL PARAMETER
BYTE bX;
BYTE bY;
BYTE bZ;
BYTE bAcclExt1;
BYTE bAcclExt2;
//ALS CONTROL PARAMETER
BYTE bAlsData;
BYTE bAlsExt1;
BYTE bAlsExt2;
//PROXIMITY CONTROL PARA
BYTE bProxiData;
WORD bProxiExt1;
WORD bProxiExt2;
Jemmey Huang
1
Wayne Zhang 2
1. Application Engineer Manager Sr.
2. Applications Engineer Staff.
Background:
Jemmey Huang is working as Sr.
Applications Engineer Manager in
Cypress Semiconductor’s Asia-Pac
Solution Center.
Contact:
[email protected]
[email protected]
BYTE bExtFun1;
BYTE bExtFun2;
}TYPE_I2CS_STRUCT;
extern TYPE_I2CS_STRUCT I2CSBuff;
//extern BYTE bgControl1,bgControl2;
void vI2CInit(void);
//void vScanI2CCmd(void);
#endif
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Document History
Document Title: Infrared Proximity Detection with PSoC®
Document Number: 001-50956
Revision
**
ECN
2635179
Orig. of
Change
JHU
Submission
Date
01/13/09
Description of Change
New Application Note
PSoC is a registered trademark of Cypress Semiconductor Corp. "Programmable System-on-Chip," PSoC Designer, and PSoC Express are
trademarks of Cypress Semiconductor Corp. All other trademarks or registered trademarks referenced herein are the property of their
respective owners.
Cypress Semiconductor
198 Champion Court
San Jose, CA 95134-1709
Phone: 408-943-2600
Fax: 408-943-4730
http://www.cypress.com/
© Cypress Semiconductor Corporation, 2009. The information contained herein is subject to change without notice. Cypress Semiconductor
Corporation assumes no responsibility for the use of any circuitry other than circuitry embodied in a Cypress product. Nor does it convey or imply any
license under patent or other rights. Cypress products are not warranted nor intended to be used for medical, life support, life saving, critical control or
safety applications, unless pursuant to an express written agreement with Cypress. Furthermore, Cypress does not authorize its products for use as
critical components in life-support systems where a malfunction or failure may reasonably be expected to result in significant injury to the user. The
inclusion of Cypress products in life-support systems application implies that the manufacturer assumes all risk of such use and in doing so indemnifies
Cypress against all charges.
This Source Code (software and/or firmware) is owned by Cypress Semiconductor Corporation (Cypress) and is protected by and subject to worldwide
patent protection (United States and foreign), United States copyright laws and international treaty provisions. Cypress hereby grants to licensee a
personal, non-exclusive, non-transferable license to copy, use, modify, create derivative works of, and compile the Cypress Source Code and derivative
works for the sole purpose of creating custom software and or firmware in support of licensee product to be used only in conjunction with a Cypress
integrated circuit as specified in the applicable agreement. Any reproduction, modification, translation, compilation, or representation of this Source
Code except as specified above is prohibited without the express written permission of Cypress.
Disclaimer: CYPRESS MAKES NO WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, WITH REGARD TO THIS MATERIAL, INCLUDING, BUT
NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. Cypress reserves the
right to make changes without further notice to the materials described herein. Cypress does not assume any liability arising out of the application or
use of any product or circuit described herein. Cypress does not authorize its products for use as critical components in life-support systems where a
malfunction or failure may reasonably be expected to result in significant injury to the user. The inclusion of Cypress’ product in a life-support systems
application implies that the manufacturer assumes all risk of such use and in doing so indemnifies Cypress against all charges.
Use may be limited by and subject to the applicable Cypress software license agreement.
January 13, 2009
Document No. 001-50956 Rev **
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