change analogWrite scheme to simply clear the timer then reconfigure

Author: oclyke

cores/arduino/ard_sup/analog/ap3_analog.cpp

@@ -119,10 +119,13 @@ static const uint8_t outcfg_tbl[32][4] =
         {OUTC(1, 7, 1), OUTC(0, 6, 0), OUTC(1, 7, 0), OUTC(1, 3, 1)}, // CTX31: B7OUT2, A6OUT,  B7OUT,  B3OUT2
 };
 
+#define AP3_MAX_ANALOG_WRITE_WIDTH 0x0000FFFF
+
 uint16_t _analogBits = 10;    //10-bit by default
 uint8_t _analogWriteBits = 8; // 8-bit by default for writes
 uint8_t _servoWriteBits = 8;  // 8-bit by default for writes
 static bool ap3_adc_initialized = false; // flag to show if the ADC has been initialized
+static uint32_t _analogWriteWidth = 0x0000FFFF;
 
 uint16_t analogRead(uint8_t pinNumber)
 {
@@ -382,92 +385,6 @@ ap3_err_t ap3_change_channel(uint8_t padNumber)
     return AP3_OK;
 }
 
-bool ap3_pwm_is_running(uint32_t ui32TimerNumber, uint32_t ui32TimerSegment)
-{
-    volatile uint32_t *pui32ConfigReg;
-    bool is_enabled = false;
-
-    //
-    // Find the correct control register.
-    //
-    pui32ConfigReg = (uint32_t *)CTIMERADDRn(CTIMER, ui32TimerNumber, CTRL0);
-
-    //
-    // Begin critical section while config registers are read and modified.
-    //
-    AM_CRITICAL_BEGIN
-
-    //
-    // Read the current value.
-    //
-    uint32_t ui32ConfigVal = *pui32ConfigReg;
-
-    //
-    // Check the "enable bit"
-    //
-    if (ui32ConfigVal & (CTIMER_CTRL0_TMRA0EN_Msk | CTIMER_CTRL0_TMRB0EN_Msk))
-    {
-        is_enabled = true;
-    }
-
-    //
-    // Done with critical section.
-    //
-    AM_CRITICAL_END
-
-    return is_enabled;
-}
-
-void ap3_pwm_wait_for_pulse(uint32_t timer, uint32_t segment, uint32_t output, uint32_t margin)
-{
-
-    volatile uint32_t *pui32CompareReg;
-    volatile uint32_t ctimer_val;
-    uint32_t cmpr0;
-
-    // Only wait if the ctimer is running to avoid a deadlock
-    if (ap3_pwm_is_running(timer, segment))
-    {
-
-        // Get the comapre register address
-        if (segment == AM_HAL_CTIMER_TIMERA)
-        {
-            if (output == AM_HAL_CTIMER_OUTPUT_NORMAL)
-            {
-                pui32CompareReg = (uint32_t *)CTIMERADDRn(CTIMER, timer, CMPRA0);
-            }
-            else
-            {
-                pui32CompareReg = (uint32_t *)CTIMERADDRn(CTIMER, timer, CMPRAUXA0);
-            }
-        }
-        else
-        {
-            if (output == AM_HAL_CTIMER_OUTPUT_NORMAL)
-            {
-                pui32CompareReg = (uint32_t *)CTIMERADDRn(CTIMER, timer, CMPRB0);
-            }
-            else
-            {
-                pui32CompareReg = (uint32_t *)CTIMERADDRn(CTIMER, timer, CMPRAUXB0);
-            }
-        }
-
-        // Get the compare value
-        cmpr0 = ((uint32_t)(*(pui32CompareReg)) & 0x0000FFFF);
-
-        if (cmpr0)
-        { // Only wait when cmpr0 is greater than 0 to avoid an infinite while loop
-            // Wait for the timer value to be less than the compare value so that it is safe to change
-            ctimer_val = am_hal_ctimer_read(timer, segment);
-            while ((ctimer_val + 0) >= cmpr0)
-            {
-                ctimer_val = am_hal_ctimer_read(timer, segment);
-            }
-        }
-    }
-}
-
 //**********************************************
 // ap3_pwm_output
 // - This function allows you to specify an arbitrary pwm output signal with a given frame width (fw) and time high (th).
@@ -582,16 +499,16 @@ ap3_err_t ap3_pwm_output(uint8_t pin, uint32_t th, uint32_t fw, uint32_t clk)
         set_periods = false; // disable setting periods when going into a forced mode
     }
 
-    // Wait until after high pulse to change the state (avoids inversion)
-    ap3_pwm_wait_for_pulse(timer, segment, output, 10);
-
     // Configure the pin
     am_hal_ctimer_output_config(timer,
                                 segment,
                                 pad,
                                 output,
                                 AM_HAL_GPIO_PIN_DRIVESTRENGTH_12MA); //
 
+    // clear timer (also stops the timer)
+    am_hal_ctimer_clear(timer, segment);
+
     // Configure the repeated pulse mode with our clock source
     am_hal_ctimer_config_single(timer,
                                 segment,
@@ -641,21 +558,32 @@ ap3_err_t analogWriteResolution(uint8_t res)
     return AP3_OK;
 }
 
+ap3_err_t analogWriteFrameWidth(uint32_t fw){
+    _analogWriteWidth = fw;
+    if(_analogWriteWidth > AP3_MAX_ANALOG_WRITE_WIDTH){
+        _analogWriteWidth = AP3_MAX_ANALOG_WRITE_WIDTH;
+    }
+    return AP3_OK;
+}
+
+ap3_err_t analogWriteFrequency(float freq){
+    _analogWriteWidth = (uint32_t)(12000000 / freq);
+    Serial.println(_analogWriteWidth);
+    if(_analogWriteWidth > AP3_MAX_ANALOG_WRITE_WIDTH){
+        return AP3_ERR;
+    }
+    if(_analogWriteWidth < 3){
+        return AP3_ERR;
+    }
+    return AP3_OK;
+}
+
 ap3_err_t analogWrite(uint8_t pin, uint32_t val)
 {
     // Determine the high time based on input value and the current resolution setting
     uint32_t clk = AM_HAL_CTIMER_HFRC_12MHZ; // Use an Ambiq HAL provided value to select which clock
-    uint32_t fw = 0xFFFF;                    // Choose the frame width in clock periods (32767 -> ~ 180 Hz)
-    if (val >= ((0x01 << _analogWriteBits) - 1))
-    {
-        val = fw; // Enable FORCE1
-    }
-    else
-    {
-        val <<= (16 - _analogWriteBits); // Shift over the value to fill available resolution
-    }
-
-    return ap3_pwm_output(pin, val, fw, clk);
+    uint32_t th = (uint32_t)(val * _analogWriteWidth) / ((0x01 << _analogWriteBits) - 1);
+    return ap3_pwm_output(pin, th, _analogWriteWidth, clk);
 }
 
 ap3_err_t servoWriteResolution(uint8_t res)

cores/arduino/ard_sup/ap3_analog.h

@@ -47,6 +47,8 @@ ap3_err_t analogReadResolution(uint8_t bits);
 
 ap3_err_t ap3_pwm_output(uint8_t pin, uint32_t th, uint32_t fw, uint32_t clk);
 ap3_err_t analogWriteResolution(uint8_t res);
+ap3_err_t analogWriteFrameWidth(uint32_t fw);
+ap3_err_t analogWriteFrequency(float freq);
 ap3_err_t analogWrite(uint8_t pin, uint32_t val);
 ap3_err_t servoWriteResolution(uint8_t res);
 uint8_t getServoResolution();