From: ian <ian>
Date: Sat, 17 May 2008 14:45:46 +0000 (+0000)
Subject: ping/pong spots loopback
X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ijackson/git?a=commitdiff_plain;h=99c019e868ceb4207c87a38ac4a2889324e8a830;p=trains.git

ping/pong spots loopback
---

diff --git a/cebpic/README.protocol b/cebpic/README.protocol
index abc89e8..f400d92 100644
--- a/cebpic/README.protocol
+++ b/cebpic/README.protocol
@@ -17,7 +17,7 @@ From host to PIC:
 
  > 1 0100 TTT  0 TTTTTTT  (a0)  POINT	  Point T fire
  > 1 1111 111  ....       (ff)  NMRADATA  NMRA data
- > 1 0001 XXX  0 XXXXXXX  (88+)	PING	  Ping `X' (please Pong `X')
+ > 1 0001 XXX  0 XXXXXXX  (88+)	PING	  Ping `X' (please Pong `X(+)0x5a')
  > 1 0010 RRR  E RRR...   (90+)	POLARITY  Set polarity
  > 1 0011 000  0 MMMMMMM  (98+)	WATCHDOG  W'dog reset, t/o <M*16>ms from now
  > 0 0010 001             (11)	ON	  Power on
@@ -61,7 +61,7 @@ From host to PIC:
 From PIC to host:
 
  < 1 001Y SSS  0 SSSSSSS  (9?)	DETECT	  Train is (Y=1) or is not (Y=0) at S
- < 1 0001 XXX  0 XXXXXXX  (88+)	PONG	  Pong `X' (reply to Ping `X')
+ < 1 0001 XXX  0 XXXXXXX  (88+)	PONG	  Pong `X' (reply to Ping `X(+)0x5a')
  < 1 100 0001  0 NNNNNNN  (ENQ) SPURIOUS  Number of spurious fault interrupts
  < 0 000 1001             (HT)  HELLO	  I am booted
  < 0 000 1011             (VT)  AAARGH	  Followed by debug chars (only)
@@ -117,19 +117,28 @@ should send FIXED but not fully reenable track power; track power
 should be reenabled when the host transmits ON.
 
 
-       Track and CDU                     Track and CDU
-        disabled      -------ON------->	  enabled
-          .     __      	      __
-         /|\   |`-._             ON  ,-'|    |
-          |         `-._          ,-'        |Short circuit detected
-	  |         OFF `-._   ,-'           |
-       OFF|                 ,-' _          FAULT
-	  |    	         ,-'     `-._        |
-	  |    	      ,-'           `-._     V
-	  	     '		       	`
-       Track disabled                     Wait for post-fault
-       CDU enabled     <-----500ms------   minimum off time
-       User Fault lit	     RETRIABLE
+       Track and CDU                     Track and CDU  ----->-----.
+        disabled      -------ON------->	  enabled              	    \
+          .     __      	      __      	       	       	     |
+         /|\   |`-._             ON  ,-'|    |,--------<-------.     |
+       	  |         `-._          ,-'        | 	       	       	|    |
+       OFF|         OFF `-._   ,-'           |Short    	       	|    |
+          |                 ,-' _       FAULT| circuit 	       	|    |
+     ,->-'|    	         ,+'     `-._        | detected        	|    |
+    /     |    	      ,-' |         `-._     V	       	       	|    |
+   |	  	     '	  |	       	`	       	        |    |
+   |   Track disabled     |               Wait for post-fault  	|    |
+   |   CDU enabled     <-----500ms------   minimum off time   	|    |
+   |   User Fault      	  |  RETRIABLE 	  User fault   	    	|    |
+   |    flashes slowly 	  |		   flashes rapidly  	|    |
+   |   	  		 / 			       	       	|    |
+    \  	       	       	'      	       	       	       	       	|    |
+     `----- Track disabled  ---------------->-------------------'   /
+       	    CDU enabled	    ----------------<----------------------'
+       	    User Fault lit     	WTIMEOUT        watchdog timer runs out
+
+
+
 
 
 If ON or OFF are issued in the first 500ms following a short circuit,
@@ -173,8 +182,9 @@ PING and PONG
 -------------
 
 The host may send PING at any time; the PIC should reply with PONG
-with the same X as was in the PING message.  The host may not send
-another PING until the first one's PONG has come back.
+with the same X as was in the PING message, but with the bottom byte
+xor'd with 0x5a..  The host may not send another PING until the first
+one's PONG has come back.
 
 
 POLARITY
diff --git a/detpic/program.asm b/detpic/program.asm
index 8f2595d..48180f1 100644
--- a/detpic/program.asm
+++ b/detpic/program.asm
@@ -179,7 +179,8 @@ command_ping
 	mov_fw	POSTINC0
 	mov_ff	INDF0, t
 	call	serial_addbyte
-	mov_fw	t
+	mov_lw	0x5a
+	xor_wfw	t
 	bra_n	command_ping_bad
 	goto	serial_addbyte_another
 
diff --git a/hostside/skelproto-pic.h b/hostside/skelproto-pic.h
index 5232693..b4ff693 100644
--- a/hostside/skelproto-pic.h
+++ b/hostside/skelproto-pic.h
@@ -40,4 +40,6 @@ struct PicInsnInfo {
 
 extern const PicInsnInfo pic_command_infos[], pic_reply_infos[];
 
+#define PING_PONG_PATTERN 0x5a
+
 #endif /*AUPROTO_PIC_H*/