Diff: main.cpp

Revision:

0:f2ba1ee4ee06

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Mon Jul 14 15:13:45 2014 +0000
@@ -0,0 +1,130 @@
+#include "mbed.h"
+
+#include <vector>
+ 
+Serial       pc(USBTX, USBRX); // tx, rx
+Serial       c2c(p13, p14);    // tx, rx
+DigitalInOut   nREQ(p15);
+DigitalInOut   nRDY(p16);
+
+
+// Fletcher checksum calculation, not optimised
+static uint16_t checkSum(uint8_t length_byte, uint8_t* buf){
+    // length is treated as 16-bit for checksum calculation
+    uint16_t sum1 = length_byte % 255;
+    uint16_t sum2 = sum1;
+ 
+    for (int i = 0; i < length_byte; i++) {
+        sum1 = (sum1 + buf[i]) % 255;
+        sum2 = (sum2 + sum1) % 255;
+    }
+ 
+    return ((sum2 << 8) | sum1);
+}
+
+void sendTestPacket(){
+    pc.printf("\n\rTX: wait for nRDY... ");
+    
+    nREQ = 0;
+    nREQ.mode(PinMode(OpenDrain));
+    nREQ.output();
+    
+    nRDY = 1;
+    nRDY.input();
+    
+    // wait for nRDY
+    while(nRDY == 1)
+        wait(0.1);
+
+    pc.printf("\n\rgot nRDY\n\r");
+    const uint8_t len = 0;
+    
+    c2c.putc(len);
+    while(!c2c.writeable())
+        ;
+    pc.printf("wrote len=%d\n\r", len);
+    uint8_t data[len==0? 256 : len];
+    for(int i = 0; i < (len==0? 256 : len); i++){
+        data[i] = uint8_t((i + 31) & 0xff);
+        c2c.putc(data[i]);
+        pc.printf(".");
+        while(!c2c.writeable())
+            ;
+    }
+    pc.printf("\n\rwrote data\n\r", len);
+    uint16_t csum = checkSum(len, data);
+    c2c.putc(uint8_t(csum & 0xff));
+    while(!c2c.writeable())
+        ;
+    c2c.putc(uint8_t((csum >> 8) & 0xff));
+    pc.printf("\n\rwrote checksum\n\r", len);
+}
+
+void receiveTestPacket(){
+    pc.printf("RX: wait for nREQ...");
+    
+    nREQ = 0;
+    nRDY = 0;
+    nREQ.mode(PinMode(OpenDrain | PullUp));
+    nRDY.mode(PinMode(OpenDrain | PullUp));
+    nREQ.output();
+    nRDY.output();    
+    
+//    nREQ.input();
+//    nRDY = 1;
+//    nRDY.mode(PinMode(OpenDrain));
+    
+    while(nREQ == 0)
+        wait(0.1);
+        
+    pc.printf("\n\rgot REQ\n\r");
+    nRDY = 1;
+    int len = c2c.getc();
+    std::vector<uint8_t> msg;
+    for(int i = 0; i < len; i++)
+        msg.push_back(c2c.getc());
+    
+    uint16_t csum = 0;
+    for(int i =0; i < 2; i++)
+        csum |= (uint16_t(c2c.getc()) << (i*8));
+    
+    
+    pc.printf("len=%d\n\r", len);
+    for(int i = 0; i < len; i++)
+        pc.printf("0x%x ", msg[i]);
+    pc.printf("\n\rcsum : 0x%x\n\r", csum);
+    
+    uint16_t check_checksum = checkSum(len, &msg[0]);
+    pc.printf("check: 0x%x\n\r", check_checksum);
+    
+    nRDY = 0;
+}
+
+int main() {
+    pc.printf("\n\r--------\n\rc2c UART Test\n\r");
+    
+    c2c.baud(38400);
+    
+//    while(1) {
+//        if(c2c.readable()) {
+//            pc.putc(c2c.getc());
+//        }
+//    }
+    
+    if(c2c.readable())
+        pc.printf("Leftover characters:");
+    while(c2c.readable())
+        pc.printf("0x%x ", int(c2c.getc()));
+    pc.printf("\n\r");
+    
+    
+    // receive rx_count things
+    int rx_count = 1;
+    while(rx_count > 0){
+        receiveTestPacket();
+    }
+    
+//    sendTestPacket();
+//    
+    pc.printf("\n\r--- complete ---\n\r");
+}
\ No newline at end of file