PCA9955A and PCA9956A class library. The PCA9955A is a 16-channel and the PCA9956A is a 24-channel Fm+ I2C-bus 57mA/20V constant current LED driver. The PCA9955A has a extended feature which called "Gradation control".
Dependents: PCA9956A_Hello pca9956b_two_demoboards PCA9955A_Gradation_control PCA9955A_Gradation_control ... more
What is this?
Code for PCA9956A and PCA9955A.
24-channel and 16-channel constant current type LED driver component class.
Please refer to the component page for details
High-level API is available
A high-level API that can be used as the "PwmOut" of bed-SDK is available.
This API enables to make instances of each LED output pins and control PWM duty cycle by assignment.
Output current also controllable by API function.
For detail information, refer API document of LedPwmOutCC Class
class which is included in PCA995xA class library.
#include "mbed.h" #include "PCA9956A.h" PCA9956A led_cntlr( p28, p27, 0xC4 ); // SDA, SCL, Slave_address(option) LedPwmOutCC led( led_cntlr, L0 ); int main() { while( 1 ) { for( float p = 0.0f; p < 1.0f; p += 0.1f ) { led = p; wait( 0.1 ); } } }
About the chips
PCA9956A
The PCA9956A is an I2C-bus controlled 24-channel constant current LED driver optimized for dimming and blinking 57 mA LEDs. Each LED output has its own 8-bit resolution (256 steps) fixed frequency individual PWM controller that operates at 31.25 kHz with a duty cycle that is adjustable from 0 % to 99.6 % to allow the LED to be set to a specific brightness value.
Datasheet: http://www.nxp.com/documents/data_sheet/PCA9956A.pdf
PCA9955A
The PCA9955A is an I2C-bus controlled 16-channel constant current LED driver optimized for dimming and blinking 57 mA Red/Green/Blue/Amber (RGBA) LEDs in amusement products. Each LED output has its own 8-bit resolution (256 steps) fixed frequency individual PWM controller that operates at 31.25 kHz with a duty cycle that is adjustable from 0 % to 100 % to allow the LED to be set to a specific brightness value.
On addition to this, the PCA9955A has "Gradation control".
The gradation control is a new feature of PCA995xA series. After the register setting and start the control, the PCA9955A performs dimming cycles automatically without MCU intervention.
Datasheet: http://www.nxp.com/documents/data_sheet/PCA9955A.pdf
PCA9952 and PCA9955 (non-A version)
The PCA9955 and PCA9955 (no-A at end of the type number) is not supported by this component class.
PCA9955(non-A)
PCA9955A != PCA9955
PCA9955A is not software compatible to PCA9955(non-A version).
There are several differences between A and non-A versions.
Register mapping is one of the difference. Please make sure you are using PCA9955A.
How the API works?
When the instance is made, all set up for PWM operation are done automatically.
For the operation, user can control the LED brightness in two ways.
- PWM
- Current
PCA9955A and PCA9956A have internal 31.25kHz oscillator to generate internal PWM waveform. This signal switchs the output current ON and OFF. The class' function pwm()
controls duty-cycle of this output.
Another control is current. Since the PCA9955A and PCA9956A are constant current type LED driver, those have internal current sources. The current source on each channels has independent control of output current. The class' function current()
provides interface to current change.
Tips for the chips
PCA995xA family
This PCA995xA components library can be used for both PCA9955A(16-channel) and PCA9956A(24-channel).
If you are using both chips on the I2C bus, those can be operated like..
#include "mbed.h" #include "PCA9955A.h" #include "PCA9956A.h" PCA9955A led0( p28, p27, 0xC0 ); // SDA, SCL, Slave_address=0xC0 (16-channel chip) PCA9956A led1( p28, p27, 0xC2 ); // SDA, SCL, Slave_address=0xC2 (24-channel chip) int main() { led0.current( ALLPORTS, 1.0 ); // Set all ports output current 100% led1.current( ALLPORTS, 1.0 ); // Set all ports output current 100% led0.pwm( .... // PWM control for PCA9955A(16-channel chip) led1.pwm( .... // PWM control for PCA9956A(24-channel chip) ...
Other sample code
For PCA9955A : http://developer.mbed.org/users/nxp_ip/code/PCA9955A_Hello/
For PCA9956A : http://developer.mbed.org/users/nxp_ip/code/PCA9956A_Hello/
For Gradation control of PCA9955A http://developer.mbed.org/users/nxp_ip/code/PCA9955A_Gradation_control/
Diff: PCA9955A/PCA9955A.h
- Revision:
- 0:a624e2eeccac
- Child:
- 1:3522be54a4f5
diff -r 000000000000 -r a624e2eeccac PCA9955A/PCA9955A.h --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/PCA9955A/PCA9955A.h Wed Feb 25 06:42:41 2015 +0000 @@ -0,0 +1,301 @@ +/** PCA9955A constant current LED driver + * + * An operation sample of PCA9955A 16-channel Fm+ I2C-bus 57mA/20V constant current LED driver. + * mbed accesses PCA9955A registers via I2C. + * + * @class PCA9955A + * @author Akifumi (Tedd) OKANO, NXP Semiconductors + * @version 0.5 + * @date 25-Feb-2015 + * + * Released under the Apache 2 license License + * + * About PCA9955A: + * http://www.nxp.com/products/interface_and_connectivity/i2c/i2c_led_display_control/PCA9955ATW.html + */ + +#ifndef MBED_PCA9955A +#define MBED_PCA9955A + +#include "mbed.h" +#include "PCA995xA.h" + +/** PCA9955A class + * + * This is a driver code for the PCA9955A 16-channel Fm+ I2C-bus 57mA/20V constant current LED driver. + * This class provides interface for PCA9955A operation and accessing its registers. + * Detail information is available on next URL. + * http://www.nxp.com/products/interface_and_connectivity/i2c/i2c_led_display_control/PCA9955ATW.html + * + * Example: + * @code + * #include "mbed.h" + * + * #include "PCA9955A.h" + * PCA9955A led_cntlr( p28, p27, 0x02 ); // SDA, SCL, Slave_address(option) + * + * int main() + * { + * led_cntlr.current( ALLPORTS, 1.0 ); // Set all ports output current 100% + * + * while(1) { + * for ( int port = 0; port < led_cntlr.number_of_ports(); port++ ) { + * for ( int i = 1; i <= 100; i++ ) { + * led_cntlr.pwm( port, (float)i / 100.0 ); + * wait( 0.01 ); + * } + * } + * led_cntlr.pwm( ALLPORTS, 0.0 ); + * } + * } + * @endcode + */ +class PCA9955A : public PCA995xA +{ +public: + /** Name of the PCA9955A registers */ + enum command_reg { + MODE1 = 0x00, + MODE2, + LEDOUT0, LEDOUT1, LEDOUT2, LEDOUT3, + GRPPWM = 0x06, + GRPFREQ, + PWM0, PWM1, PWM2, PWM3, + PWM4, PWM5, PWM6, PWM7, + PWM8, PWM9, PWM10, PWM11, + PWM12, PWM13, PWM14, PWM15, + IREF0, IREF1, IREF2, IREF3, + IREF4, IREF5, IREF6, IREF7, + IREF8, IREF9, IREF10, IREF11, + IREF12, IREF13, IREF14, IREF15, + RAMP_RATE_GRP0, STEP_TIME_GRP0, HOLD_CNTL_GRP0, IREF_GRP0, + RAMP_RATE_GRP1, STEP_TIME_GRP1, HOLD_CNTL_GRP1, IREF_GRP1, + RAMP_RATE_GRP2, STEP_TIME_GRP2, HOLD_CNTL_GRP2, IREF_GRP2, + RAMP_RATE_GRP3, STEP_TIME_GRP3, HOLD_CNTL_GRP3, IREF_GRP3, + GRAD_MODE_SEL0 = 0x38, + GRAD_MODE_SEL1, + GRAD_GRP_SEL0, GRAD_GRP_SEL1, GRAD_GRP_SEL2, GRAD_GRP_SEL3, + GRAD_CNTL, + OFFSET = 0x3F, + SUBADR1, SUBADR2, SUBADR3, ALLCALLADR, + PWMALL, IREFALL, + EFLAG0, EFLAG1, + + REGISTER_START = MODE1, + LEDOUT_REGISTER_START = LEDOUT0, + PWM_REGISTER_START = PWM0, + IREF_REGISTER_START = IREF0, + GRAD_GROUP_OFFSET = RAMP_RATE_GRP1 - RAMP_RATE_GRP0 + }; + + /** Create a PCA9629A instance connected to specified I2C pins with specified address + * + * @param i2c_sda I2C-bus SDA pin + * @param i2c_sda I2C-bus SCL pin + * @param i2c_address (option) I2C-bus address (default: 0xC0) + */ + PCA9955A( PinName i2c_sda, PinName i2c_scl, char i2c_address = PCA995xA::DEFAULT_I2C_ADDR ); + + /** Create a PCA9629A instance connected to specified I2C pins with specified address + * + * @param i2c_obj I2C object (instance) + * @param i2c_address (option) I2C-bus address (default: 0xC0) + */ + PCA9955A( I2C &i2c_obj, char i2c_address = PCA995xA::DEFAULT_I2C_ADDR ); + + /** Destractor + * + */ + virtual ~PCA9955A(); + + /** Returns the number of output ports + * + * @returns + * The number of output ports + */ + virtual int number_of_ports( void ); + +#if DOXYGEN_ONLY + /** Set the output duty-cycle, specified as a percentage (float) + * + * @param port Selecting output port + * 'ALLPORTS' can be used to set all port duty-cycle same value. + * @param v A floating-point value representing the output duty-cycle, + * specified as a percentage. The value should lie between + * 0.0f (representing on 0%) and 1.0f (representing on 100%). + * Values outside this range will have undefined behavior. + */ + void pwm( int port, float v ); + + /** Set all output port duty-cycle, specified as a percentage (array of float) + * + * @param vp Aray to floating-point values representing the output duty-cycle, + * specified as a percentage. The value should lie between + * 0.0f (representing on 0%) and 1.0f (representing on 100%). + * + * @note + * The aray should have length of 16 + */ + void pwm( float *vp ); + + /** Set the output current, specified as a percentage (float) + * + * @param port Selecting output port + * 'ALLPORTS' can be used to set all port duty-cycle same value. + * @param v A floating-point value representing the output current, + * specified as a percentage. The value should lie between + * 0.0f (representing on 0%) and 1.0f (representing on 100%). + * Values outside this range will have undefined behavior. + */ + void current( int port, float vp ); + + /** Set all output port curent, specified as a percentage (array of float) + * + * @param vp Aray to floating-point values representing the output current, + * specified as a percentage. The value should lie between + * 0.0f (representing on 0%) and 1.0f (representing on 100%). + * + * @note + * The aray should have length of 16 + */ + void current( float *vP ); + + /** Register write (single byte) : Low level access to device register + * + * @param reg_addr Register address + * @param data Value for setting into the register + */ + void write( char reg_addr, char data ); + + /** Register write (multiple bytes) : Low level access to device register + * + * @param data Pointer to an array. First 1 byte should be the writing start register address + * @param length Length of data + */ + void write( char *data, int length ); + + /** Register read (single byte) : Low level access to device register + * + * @param reg_addr Register address + * @return Read value from register + */ + char read( char reg_addr ); + + /** Register write (multiple bytes) : Low level access to device register + * + * @param reg_addr Register address + * @param data Pointer to an array. The values are stored in this array. + * @param length Length of data + */ + void read( char reg_addr, char *data, int length ); +#endif + + /** Gradation control setting + * + * Auto calculation and register setting API for gradation control. + * User can set the gradation by specifying cycle, hold-ON/OFF time and ramp-up/down enabling. + * All register values are calcurated automatically to have fine gradation setting. + * In this routine, the IREF (current) setting is fixed to maximum (i.e. 0xFF) + * + * @param group Group selector + * @param cycle Ramp rate register (RAMP_RATE_GRPn) value + * @param flag_on Holding time for ON can be selected from available constants. + * Those are 0, 0.25, 0.5, 0.75, 1, 2, 4 and 6 seconds. + * Use one of next words: HOLD_0_00_SEC, HOLD_0_25_SEC, HOLD_0_50_SEC, HOLD_0_75_SEC, HOLD_1_00_SEC, HOLD_2_00_SEC, HOLD_4_00_SEC or HOLD_6_00_SEC + * @param flag_off Holding time for OFF can be selected from available constants. + * Those are 0, 0.25, 0.5, 0.75, 1, 2, 4 and 6 seconds. + * Use one of next words: HOLD_0_00_SEC, HOLD_0_25_SEC, HOLD_0_50_SEC, HOLD_0_75_SEC, HOLD_1_00_SEC, HOLD_2_00_SEC, HOLD_4_00_SEC or HOLD_6_00_SEC + * @param ramp_flag Choose one from next words : NO_RAMP, RAMP_UP_ONLY, RAMP_DOWN_ONLY or RAMP_UP_DOWN + * + * @return calculated actual time for one cycle (in seconds) + * + * @see gradation_setting() + */ + float gradation_ramp_setting( char group, float cycle, char flag_on, char flag_off, int ramp_flag ); + + /** Gradation control: Port assignment to group + * + * Each ports which is going to use in gradation control should be assigned to group. + * This function help to assign the port to 1 of 4 groups. + * + * @param group Target group + * @param port A output port which is being assigned to the target group + */ + void gradation_group_setting( char group, char port ); + + /** Gradation control: Start + * + * @param group Group selector + * @param continuous_flag (option) Set false for one-shot operation + */ + void gradation_start( char group, char continuous_flag = true ); + + /** Gradation control: Stop + * + */ + void gradation_stop( void ); + + + /** Gradation control: Clear all group assignments + * + * Set all output port operation to no-gradation control + * + */ + void gradation_group_clear( void ); + + /** Setting gradation control registers (low level setting API) + * + * @param group Group selector + * @param ramp_rate Ramp rate register (RAMP_RATE_GRPn) value + * @param step_time Step time register (STEP_TIME_GRPn) value + * @param hold_cntl Hold control register (HOLD_CNTL_GRPn) value + * @param iref IREF (current setting) register (IREF_GRPn) value + * + * @see gradation_ramp_setting() + */ + void gradation_setting( int group, char ramp_rate, char step_time, char hold_cntl, char iref ); + + /** Setting gradation register dump (for debugging) + * + */ + void dump_gradation_registers( void ); + +private: + void initialize( void ); + virtual char pwm_register_access( int port ); + virtual char current_register_access( int port ); + + void group_selector( short g0, short g1, short g2, short g3 ); + + const int n_of_ports; + static char gradation_group[]; +} +; + +/** Constants for Gradation control */ +enum GradationControlConstants { + CONTINUOUS = 1, + NOGROUP = 0xFF +}; + +/** Flags for Gradation control (Ramp selector) */ +enum GradationControlRampSelector { + NO_RAMP = 0x0, + RAMP_UP_ONLY, + RAMP_DOWN_ONLY, + RAMP_UP_DOWN +}; + +/** Flags for Gradation control (Hold time selector) */ +enum GradationControlHoldTimeSelector { + HOLD_0_00_SEC = 0x0, + HOLD_0_25_SEC, + HOLD_0_50_SEC, + HOLD_0_75_SEC, + HOLD_1_00_SEC, + HOLD_2_00_SEC, + HOLD_4_00_SEC, + HOLD_6_00_SEC +}; + +#endif // MBED_PCA9955A