bitbanging works

Author: geohot

board/drivers/canbitbang.h

@@ -42,43 +42,54 @@ int append_crc(char *in, int in_len) {
   return in_len;
 }
 
-int get_bit_message(char *out) {
-  char test_pkt[MAX_BITS_CAN_PACKET];
-  char test_pkt_src[] = {
-    0, // SOF
-    0,0,0,0, // ID10-ID7
-    0,0,1,0,1,0,0,   // ID6-ID0
-    0, // RTR
-    0, // IDE
-    0, // reserved
-    0,0,0,1, // len
-    0,0,0,0,0, // 1st byte 7-3
-    0,0,1,     // 1st byte 2-0
-  };
+int append_bits(char *in, int in_len, char *app, int app_len) {
+  for (int i = 0; i < app_len; i++) {
+    in[in_len++] = app[i];
+  }
+  return in_len;
+}
 
+int append_int(char *in, int in_len, int val, int val_len) {
+  for (int i = val_len-1; i >= 0; i--) {
+    in[in_len++] = (val&(1<<i)) != 0;
+  }
+  return in_len;
+}
+
+int get_bit_message(char *out, CAN_FIFOMailBox_TypeDef *to_bang) {
+  char pkt[MAX_BITS_CAN_PACKET];
   char footer[] = {
     1,  // CRC delimiter
-
     1,  // ACK
     1,  // ACK delimiter
     1,1,1,1,1,1,1, // EOF
     1,1,1, // IFS
   };
   #define SPEEED 30
 
-  // copy packet
-  for (int i = 0; i < sizeof(test_pkt_src); i++) test_pkt[i] = test_pkt_src[i];
+  int len = 0;
+
+  // test packet
+  int dlc_len = to_bang->RDTR & 0xF;
+  len = append_int(pkt, len, 0, 1);    // Start-of-frame
+  len = append_int(pkt, len, to_bang->RIR >> 21, 11);  // Identifier
+  len = append_int(pkt, len, 0, 3);    // RTR+IDE+reserved
+  len = append_int(pkt, len, dlc_len, 4);    // Data length code
+
+  // append data
+  for (int i = 0; i < dlc_len; i++) {
+    unsigned char dat = ((unsigned char *)(&(to_bang->RDLR)))[i];
+    len = append_int(pkt, len, dat, 8);
+  }
 
   // append crc
-  int len = append_crc(test_pkt, sizeof(test_pkt_src));
+  len = append_crc(pkt, len);
 
   // do bitstuffing
-  len = do_bitstuff(out, test_pkt, len);
+  len = do_bitstuff(out, pkt, len);
 
   // append footer
-  for (int i = 0; i < sizeof(footer); i++) {
-    out[len++] = footer[i];
-  }
+  len = append_bits(out, len, footer, sizeof(footer));
   return len;
 }
 
@@ -100,7 +111,7 @@ void bitbang_gmlan(CAN_FIFOMailBox_TypeDef *to_bang) {
   puts("\n");
 
   char pkt_stuffed[MAX_BITS_CAN_PACKET];
-  int len = get_bit_message(pkt_stuffed);
+  int len = get_bit_message(pkt_stuffed, to_bang);
 
   // actual bitbang loop
   set_bitbanged_gmlan(1); // recessive

tests/gmbitbang/test.py

@@ -19,9 +19,9 @@
 # send w bitbang then without
 while 1:
   p1.set_gmlan(bus=None)
-  p1.can_send(20, "\x01", bus=3)
+  p1.can_send(123, "\x01\x02\x03\x04\x05\x06\x07\x08", bus=3)
   p1.set_gmlan(bus=2)
-  p1.can_send(20, "\x01", bus=3)
+  p1.can_send(123, "\x01\x02\x03\x04\x05\x06\x07\x08", bus=3)
   time.sleep(0.01)
   print p2.can_recv()
 

tests/gmbitbang/test_packer.c

@@ -1,9 +1,23 @@
 #include <stdio.h>
+#include <stdint.h>
+
+typedef struct {                        
+  uint32_t RIR;  /*!< CAN receive FIFO mailbox identifier register */                                               
+  uint32_t RDTR; /*!< CAN receive FIFO mailbox data length control and time stamp register */                       
+  uint32_t RDLR; /*!< CAN receive FIFO mailbox data low register */                                                 
+  uint32_t RDHR; /*!< CAN receive FIFO mailbox data high register */                                                
+} CAN_FIFOMailBox_TypeDef; 
+
 #include "../../board/drivers/canbitbang.h"
 
 int main() {
-  char out[100];
-  int len = get_bit_message(out);
+  char out[300];
+  CAN_FIFOMailBox_TypeDef to_bang = {0};
+  to_bang.RIR = 20 << 21;
+  to_bang.RDTR = 1;
+  to_bang.RDLR = 1;
+
+  int len = get_bit_message(out, &to_bang);
   printf("T:");
   for (int i = 0; i < len; i++) {
     printf("%d", out[i]);