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update RTC code

This commit is contained in:
Kyle Isom 2025-04-04 16:24:36 -07:00
parent 3d3b27baad
commit bf7af0e761
1 changed files with 21 additions and 12 deletions
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33
lisp/rtc.lsp
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@ -1,16 +1,5 @@
(defvar *rtc-port* 0) (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) (defun bcd-to-dec (x)
"(bcd-to-dec x) "(bcd-to-dec x)
Convert the BCD-encoded number x to a decimal value." 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) (defun dec-to-bcd (x)
"(dec-to-bcd x) "(dec-to-bcd x)
Converts the decimal value to a BCD-encoded number. 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 () (defun rtc-get ()
(with-i2c (str *rtc-port* #x68) (with-i2c (str *rtc-port* #x68)
@ -40,4 +46,7 @@ Set the time using the RTC."
(apply now (rtc-get))) (apply now (rtc-get)))
(defun now-rtc () (defun now-rtc ()
"(now-rtc)
Sets the RTC time using the now function."
(apply rtc-set (now)))