From e9f3d4a56d10de933c9c22646a7b084ec3cff20f Mon Sep 17 00:00:00 2001
From: RossTheRoss <msattr@gmail.com>
Date: Fri, 24 Apr 2020 13:16:17 -0500
Subject: Add MORE stuff I forget to commit

---
 HW4.X/hw4_uart_caesar_cipher_strap012.c | 109 ++++++++++++++++++++++++++++++++
 1 file changed, 109 insertions(+)
 create mode 100644 HW4.X/hw4_uart_caesar_cipher_strap012.c

(limited to 'HW4.X/hw4_uart_caesar_cipher_strap012.c')

diff --git a/HW4.X/hw4_uart_caesar_cipher_strap012.c b/HW4.X/hw4_uart_caesar_cipher_strap012.c
new file mode 100644
index 0000000..af2e50e
--- /dev/null
+++ b/HW4.X/hw4_uart_caesar_cipher_strap012.c
@@ -0,0 +1,109 @@
+#include <p24Fxxxx.h>
+#include <xc.h>
+#include <stdlib.h>
+
+// PIC24FJ64GA002 Configuration Bit Settings
+// CW1: FLASH CONFIGURATION WORD 1 (see PIC24 Family Reference Manual 24.1)
+#pragma config ICS = PGx1          // Comm Channel Select (Emulator EMUC1/EMUD1 pins are shared with PGC1/PGD1)
+#pragma config FWDTEN = OFF        // Watchdog Timer Enable (Watchdog Timer is disabled)
+#pragma config GWRP = OFF          // General Code Segment Write Protect (Writes to program memory are allowed)
+#pragma config GCP = OFF           // General Code Segment Code Protect (Code protection is disabled)
+#pragma config JTAGEN = OFF        // JTAG Port Enable (JTAG port is disabled)
+
+
+// CW2: FLASH CONFIGURATION WORD 2 (see PIC24 Family Reference Manual 24.1)
+#pragma config POSCMOD = NONE           // Primary Oscillator Select (Primary oscillator disabled. 
+					// Primary Oscillator refers to an external osc connected to the OSC1 and OSC2 pins)
+#pragma config I2C1SEL = PRI       // I2C1 Pin Location Select (Use default SCL1/SDA1 pins)
+#pragma config IOL1WAY = OFF       // IOLOCK Protection (IOLOCK may be changed via unlocking seq)
+#pragma config OSCIOFNC = ON       // OSC2/CLKO/RC15 functions as port I/O (RC15)
+#pragma config FCKSM = CSECME      // Clock Switching and Monitor (Clock switching is enabled, 
+                                       // Fail-Safe Clock Monitor is enabled)
+#pragma config FNOSC = FRCPLL      // Oscillator Select (Fast RC Oscillator with PLL module (FRCPLL))
+
+volatile unsigned char buffer[64];
+volatile unsigned char front = 0;
+volatile unsigned char back = 0;
+
+void __attribute__((__interrupt__,__auto_psv__)) _U1RXInterrupt(void)
+{
+    IFS0bits.U1RXIF = 0;
+    buffer[front++] = U1RXREG;
+    front &= 63;
+}
+
+void PPutch(const unsigned char c)
+{
+    while (!IFS0bits.U1TXIF) ;
+    IFS0bits.U1TXIF = 0;
+    U1TXREG = ((c+3-65) %26) + 65;
+}
+
+unsigned char PGetch(void)
+{
+    unsigned char x;
+
+    while (front == back) ;
+    x = buffer[back++];
+    back &= 63;
+    return x;
+}
+
+void setup(void)
+{
+    CLKDIVbits.RCDIV = 0;
+    AD1PCFG = 0x9fff;  // For digital I/O.
+    
+    // I think the following two lines are irrelevant. The UART doc
+    // Page 3, when describing the UARTEN bit in UxMODE says that when UARTEN
+    // is set, TRISx are ignored and instead UEN and UTXEN control pins.
+    _TRISB6 = 0;  // U1TX output
+    _TRISB10 = 1; // U1RX input
+
+    U1MODE = 0;  // UEN<1:0> bits control the pins
+    // U1BRG = 34; // 115200 baud,
+    // U1MODEbits.BRGH = 1;
+    U1MODEbits.BRGH = 0;
+    U1BRG = 25; // 38400 baud (check the calculation with the datasheet)
+    U1MODEbits.UEN = 0;
+    U1MODEbits.UARTEN = 1;
+    U1STAbits.UTXEN = 1;
+
+    // Peripheral Pin Select 
+    __builtin_write_OSCCONL(OSCCON & 0xbf); // unlock PPS
+    _RP6R = 0x0003;   //RB6->UART1:U1TX; See Table 10-3 on P109 of the datasheet
+    _U1RXR = 10;   //RB10->UART1:U1RX;
+    __builtin_write_OSCCONL(OSCCON | 0x40); // lock   PPS
+
+    IFS0bits.U1RXIF = 0;
+    IEC0bits.U1RXIE = 1;
+}
+
+int main(int argc, char *argv[])
+{
+
+    setup();
+
+    int i;
+
+    // waste some time
+    for (i = 0; i < 30000; i++) i = i;
+
+    // transmit data on UART
+//    for (i = ' '; i < 0x7f; i++)
+//        PPutch(i);
+    PPutch(0x0D);  // new line characters
+    PPutch(0x0A);
+
+    while (1)
+    {
+        unsigned int x;
+
+        x = PGetch();
+        if (x>='a' && x<='z')
+            x += 'A' - 'a';
+        PPutch(x);
+    }
+
+    return 0; // never reached (we hope)
+}
\ No newline at end of file
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