Diff: PCA9685.cpp

Revision:

0:dbef204fd840

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/PCA9685.cpp	Wed Jun 20 20:09:53 2018 +0000
@@ -0,0 +1,167 @@
+#ifndef PCA9685_LIBRARY_CPP
+#define PCA9685_LIBRARY_CPP
+
+
+#include "mbed.h"
+#include "PCA9685.h"
+#include "definitions.h"
+
+
+PCA9685::PCA9685(uint8_t i2c_address, I2C i2c_object, float frequency) :
+
+    i2c_addr(i2c_address),
+    freq(frequency),
+    i2c(i2c_object)
+
+{
+
+}
+
+void PCA9685::init(void)
+{
+
+    reset();
+
+    uint8_t prescale = (uint8_t) (OSC_CLOCK / (4096 * PWM_SCALER * freq)) - 1;
+
+    write_8(MODE1, 0x21); //0010 0001 : AI ENABLED
+    write_8(MODE2, 0x07); //0000 0111 : NOT INVRT, CHANGE ON STOP, TOTEM POLE, \OE = 1, LEDn = HIGH IMP
+
+    set_prescale(prescale);
+
+}
+
+void PCA9685::reset(void)
+{
+
+    write_8(MODE1,0x00);
+
+}
+
+void PCA9685::set_prescale(uint8_t prescale)
+{
+
+    uint8_t oldmode = read_8(MODE1);
+    uint8_t newmode = (oldmode&0x7F) | 0x10; // set the sleep bit
+
+    write_8(MODE1, newmode); // send the device to sleep
+    wait_ms(5);
+    write_8(PRESCALE, prescale); // set the prescaler
+    write_8(MODE1, oldmode);
+    wait_ms(5);
+    write_8(MODE1, oldmode | 0xa1); // wake up the device
+
+}
+
+
+//NB REQUIRES AUTO-INCREMENT MODE ENABLED
+//0 <= pwm_output <= 15
+//0 <= (count_on || count_off) <= 4095
+void PCA9685::set_pwm_output(int pwm_output, uint16_t count_on, uint16_t count_off)
+{
+
+    char msg[5];
+
+    msg[0] = LED0_ON_L + (4 * pwm_output);
+    msg[1] = count_on;
+    msg[2] = count_on >> 8;
+    msg[3] = count_off;
+    msg[4] = count_off >> 8;
+
+    i2c.write(i2c_addr, msg, 5);
+
+}
+
+void PCA9685::set_pwm_output_on_0(int pwm_output, uint16_t count_off)
+{
+
+    char msg[3];
+
+    msg[0] = LED0_ON_L + 2 + (4 * pwm_output);
+    msg[1] = count_off;
+    msg[2] = count_off >> 8;
+
+    i2c.write(i2c_addr,msg,3);
+
+}
+
+
+//NB REQUIRES AUTO-INCREMENT MODE ENABLED
+//0 <= pwm_output <= 15
+void PCA9685::set_pwm_duty(int pwm_output, float duty_cycle)
+{
+
+    if (duty_cycle > 1.0) {
+        duty_cycle = 1.0;
+    }
+    if (duty_cycle < 0.0) {
+        duty_cycle = 0.0;
+    }
+
+    uint16_t count_off = (uint16_t) (duty_cycle * 4095);
+    uint16_t count_on = 0x0000;
+
+    set_pwm_output(pwm_output, count_on, count_off);
+
+}
+
+
+//NB REQUIRES AUTO-INCREMENT MODE ENABLED
+//0 <= pwm_output <= 15
+void PCA9685::set_pwm_pw(int pwm_output, float pulse_width_us)
+{
+
+    float period_us = (1e6/freq);
+
+    float duty = pulse_width_us/period_us;
+
+    set_pwm_duty(pwm_output, duty);
+
+}
+
+
+void PCA9685::update(void)
+{
+
+    i2c.stop();
+
+}
+
+
+
+void PCA9685::write_8(uint8_t reg, uint8_t msg)
+{
+
+    char send[2]; //Store the address and data in an array
+    send[0] = reg;
+    send[1] = msg;
+    i2c.write(i2c_addr, send, 2);
+
+}
+
+uint8_t PCA9685::read_8(uint8_t reg)
+{
+
+    char send[1] ;
+    send[0] = reg;
+    i2c.write(i2c_addr, send, 1);
+    char recieve[1];
+    i2c.read(i2c_addr, recieve, 1);
+    return recieve[0];
+
+}
+
+int PCA9685::convert_pwm_value(float pulse_width_us, float period_us)
+{
+
+    int result;
+    float interim;
+
+    interim = ((pulse_width_us / period_us) * 4095); //scale the pulse width to a 12-bit scale
+    result = (int) interim; //round the value to the nearest integer
+
+    return result;
+
+}
+
+#endif
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