lisp/rtc.lsp

@@ -1,16 +1,5 @@
 (defvar *rtc-port* 0)
 
-(defun rtc-set (hr min)
- "(rtc-set hr min)
-Set the time on a DS3231 RTC. Times are in BCD, so use
-the appropriate reader macro, e.g. (rtc-set #x12 #x34)
-for 12:34. Assumes seconds are zero."
-  (with-i2c (str *rtc-port* #x68)
-    (write-byte 0 str)
-    (write-byte 0 str)
-    (write-byte min str)
-    (write-byte hr str)))
-
 (defun bcd-to-dec (x)
    "(bcd-to-dec x)
 Convert the BCD-encoded number x to a decimal value."
@@ -21,7 +10,24 @@ Convert the BCD-encoded number x to a decimal value."
 (defun dec-to-bcd (x)
   "(dec-to-bcd x)
 Converts the decimal value to a BCD-encoded number.
-Number must be in the range 0 to 99.")
+Number must be in the range 0 to 99."
+  (+
+    (ash (floor x 10) 4)
+    (logand (rem x 10) #xf)))
+
+(defun rtc-set (h m s)
+ "(rtc-set hr min sec)
+Set the time on a DS3231 RTC. Times are in BCD, so use
+the appropriate reader macro, e.g. (rtc-set #x12 #x34 #x00)
+for 12:34:00."
+  (let ((h (dec-to-bcd h))
+	(m (dec-to-bcd m))
+	(s (dec-to-bcd s)))
+    (with-i2c (str *rtc-port* #x68)
+	      (write-byte 0 str)
+	      (write-byte s str)
+	      (write-byte m str)
+	      (write-byte h str)))
 
 (defun rtc-get ()
   (with-i2c (str *rtc-port* #x68)
@@ -40,4 +46,7 @@ Set the time using the RTC."
   (apply now (rtc-get)))
 
 (defun now-rtc ()
+  "(now-rtc)
+Sets the RTC time using the now function."
+  (apply rtc-set (now)))