feat: pwm dac demo

demo/pwm/pwm_dac_voice/main.c

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+// Copyright 2021 IOsetting <iosetting(at)outlook.com>
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+/**
+ * Demo: DAC voice output simulation
+ * Board: STC8H3K32 (types with flash size >= 32KB)
+ * 
+ * P1.0  -> Speaker +
+ * GND   -> Speaker -
+*/
+#include "fw_hal.h"
+#include "voice.h"
+
+uint8_t dc = 0;
+uint16_t voice_pos = 0, voice_size = 27451;
+
+void PWM_Init()
+{
+    // Set GPIO pins output mode P10 -> PWMA.1P
+    GPIO_P1_SetMode(GPIO_Pin_0, GPIO_Mode_Output_PP);
+    // Turn off PWMA.1 before change its mode
+    PWMA_PWM1_SetPortState(HAL_State_OFF);
+    PWMA_PWM1N_SetPortState(HAL_State_OFF);
+    // Set PWMA.1 port direction output
+    PWMA_PWM1_SetPortDirection(PWMB_PortDirOut);
+    // Set PWMA.1 output low voltage when counter is less than target value
+    PWMA_PWM1_ConfigOutputMode(PWM_OutputMode_PWM_HighIfLess);
+    // Enable comparison value preload to make duty cycle changing smooth
+    PWMA_PWM1_SetComparePreload(HAL_State_ON);
+    // Turn on PWMA.1
+    PWMA_PWM1_SetPortState(HAL_State_ON);
+
+    // Set PWM frequency to 16kHz, Fpwm = SYSCLK / (PWMx_PSCR + 1) / (PWMx_ARR + 1)
+    PWMA_SetPrescaler(8);
+    // PWM width = Period + 1 (side alignment), or AutoReloadPeriod * 2 (center alignment)
+    PWMA_SetPeriod(0xFF);
+    // Counter direction, down:from [PWMA_ARRH,PWMA_ARRL] to 0
+    PWMA_SetCounterDirection(PWM_CounterDirection_Down);
+    // Enable preload on reload-period
+    PWMA_SetAutoReloadPreload(HAL_State_ON);
+    // Enable output on PWMA.1P
+    PWMA_SetPinOutputState(PWM_Pin_1, HAL_State_ON);
+    // Set PWMA.1 alternative ports to P1.0 and P1.1
+    PWMA_PWM1_SetPort(PWMA_PWM1_AlterPort_P10_P11);
+    // Enable overall output
+    PWMA_SetOverallState(HAL_State_ON);
+    // Start counter
+    PWMA_SetCounterState(HAL_State_ON);
+}
+
+void Timer0_Init()
+{
+    TIM_Timer0_Config(HAL_State_ON, TIM_TimerMode_16BitAuto, 8000);
+    EXTI_Timer0_SetIntState(HAL_State_ON);
+    EXTI_Timer0_SetIntPriority(EXTI_IntPriority_High);
+    EXTI_Global_SetIntState(HAL_State_ON);
+    TIM_Timer0_SetRunState(HAL_State_ON);
+}
+
+INTERRUPT(Timer0_Routine, EXTI_VectTimer0)
+{
+    uint8_t dc;
+    dc = voice_bulk[voice_pos++];
+    PWMA_PWM1_SetCaptureCompareValue(dc);
+    if (voice_pos == voice_size) voice_pos = 0;
+}
+
+void main(void)
+{
+    SYS_SetClock();
+    PWM_Init();
+    Timer0_Init();
+
+    while(1);
+}

demo/pwm/pwm_dac_voice/voice.h

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+#include "fw_hal.h"
+
+extern __CODE uint8_t voice_bulk[];