From 6679708c8dc5c9fa119f692a97321fa1ec715f31 Mon Sep 17 00:00:00 2001
From: William Harrington <kb0iic@berzerkula.org>
Date: Wed, 31 Jul 2019 23:15:39 -0500
Subject: Add Adc_Init and redo Adc_Read. Rework comments.

---
 adc.c | 33 +++++++++++++++++++++++----------
 adc.h |  3 +++
 2 files changed, 26 insertions(+), 10 deletions(-)

diff --git a/adc.c b/adc.c
index 81913ac..801fed0 100644
--- a/adc.c
+++ b/adc.c
@@ -1,14 +1,27 @@
 #include "adc.h"
 
-unsigned int Adc_Read(unsigned int channel) {
-    ADFM = 1; // results right justified
-    ADCS0 = 1; //conversion speed = 64*Tosc
+/* ADCON0: bit 7 - bit 0 (11-1 pg 111)
+ *         ADCS1:ADCS0:CHS2:CHS1:CHS0:GO/DONE:-:ADON
+ * 
+ * ADCON1: bit 7 - bit 0
+ *         ADFM:-:-:-:PCFG3:PCFG2:PCFG1:PCFG0
+ */
+
+void Adc_Init(void) {
+    ADCON0 = 0x00; // A/D Off, GO_DONE not in progress, Channel 0, Fosc/2
+    ADCS0 = 0; // A/D Conversion Fosc/32 ADCS1:ADCS0 (0b10) (Table 11-1)
     ADCS1 = 1;
-    ADCS2 = 1;
-    ADCON0bits.CHS = channel;
-    ADON = 1; // Turn on ADC
-    __delay_ms(1);
-    GO_DONE = 1;
-    while (ADCON0bits.GO_DONE == 1);
-    return ((ADRESH << 8) + ADRESL); // ex 1024
+
+    //ADCON1
+    ADFM = 1; // results right justified
+    PCFG0 = PCFG1 = PCFG2 = PCFG3 = 0; // AN0-AN7 Analog input, Vref+/- Vdd/Vss
+}
+
+unsigned int Adc_Read(unsigned int channel) {
+    ADCON0bits.CHS = channel; // Set CHS bits for channel (pg111)
+    ADCON0bits.ADON = 1; // Turn on ADC
+    __delay_us(5); // Enough time for A/D acquisition
+    ADCON0bits.GO_DONE = 1; // A/D Conversion bit set 1 (conversion in progress)
+    while (ADCON0bits.GO_DONE == 1); // Wait for conversion to finish
+    return ((ADRESH << 8) + ADRESL); // return combined 10 bits of conversion
 }
\ No newline at end of file
diff --git a/adc.h b/adc.h
index 39bc940..d214580 100644
--- a/adc.h
+++ b/adc.h
@@ -1,4 +1,7 @@
 #include "conf.h"
 
+// Initialize ADC
+void Adc_Init(void);
+
 // Get ADC value
 unsigned int Adc_Read(unsigned int);
\ No newline at end of file
-- 
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