opt: add adc polling methods

include/fw_adc.h

@@ -92,6 +92,14 @@
 */
 #define ADC_SetSampleTime(__CLKS_1TO32__)       (ADCTIM = ADCTIM & ~(0x1F << 0) | ((__CLKS_1TO32__) << 0))
 
+/**
+ * Start ADC conversion, and return 8-bit result
+*/
+uint8_t ADC_Convert(void);
 
+/**
+ * Start ADC conversion, and return 16-bit high precision result
+*/
+uint16_t ADC_ConvertHP(void);
 
 #endif

src/fw_adc.c

@@ -0,0 +1,38 @@
+// 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.
+
+#include "fw_adc.h"
+
+
+uint8_t ADC_Convert(void)
+{
+    ADC_Start();
+    NOP();
+    NOP();
+    while (!ADC_SamplingFinished());
+    ADC_ClearInterrupt();
+    return ADC_RES;
+}
+
+uint16_t ADC_ConvertHP(void)
+{
+    int16_t res;
+    ADC_Start();
+    NOP();
+    NOP();
+    while (!ADC_SamplingFinished());
+    ADC_ClearInterrupt();
+    res = ADC_RES;
+    return (res << 8) + ADC_RESL;
+}