Revision: 1895
Author: [email protected]
Date: Wed Apr 7 21:00:56 2010
Log: sample for timer
http://code.google.com/p/jallib/source/detail?r=1895
Added:
/trunk/sample/18f452_timer3_rtc.jal
=======================================
--- /dev/null
+++ /trunk/sample/18f452_timer3_rtc.jal Wed Apr 7 21:00:56 2010
@@ -0,0 +1,144 @@
+-- Title: second counter using timer3
+-- Author: Matthew Schinkel - borntechi.com, copyright (c) 2009, all
rights reserved.
+-- Adapted-by:
+-- Compiler: >=2.4m
+--
+-- This file is part of jallib (http://jallib.googlecode.com)
+-- Released under the BSD license
(http://www.opensource.org/licenses/bsd-license.php)
+--
+-- Description: counts seconds with timer3
+--
+-- Sources:
+--
+-- notes:
+--
+
+-- include chip
+include 18F452 -- target picmicro
+
+-- This program assumes a 20 MHz resonator or crystal
+-- is connected to pins OSC1 and OSC2.
+pragma target clock 20_000_000 -- oscillator frequency
+-- configuration memory settings (fuses)
+pragma target OSC HS -- HS crystal or resonator
+pragma target WDT disabled -- no watchdog
+pragma target LVP disabled -- no Low Voltage Programming
+
+-- set all IO as digital
+enable_digital_io()
+
+-- led def
+alias led is pin_a1
+alias led_direction is pin_a1_direction
+--
+led_direction = output
+
+-- setup uart for communication
+const serial_hw_baudrate = 115200 -- set the baudrate
+include serial_hardware
+serial_hw_init()
+
+serial_hw_data = 0xAA
+serial_hw_data = 0xAA
+serial_hw_data = 0xAA
+serial_hw_data = 0xAA
+
+include print
+
+-- init pic interrupt settings
+intcon_gie = on ; enables all unmasked interrupts
+intcon_peie = on ; enables all unmasked peripheral interrupts
+
+-- Set this to desired interval. timer3 will count up.
+-- Interupt will occur when timer_interval rolls
+-- over from 65535 to 0
+var word timer_interval = 0
+
+-- timer3 setup
+tmr3 = timer_interval -- timer interval
+t3con_tmr3cs = 0 -- use internal clock
+pie2_tmr3ie = 1 -- enable the timer3 interrupt bit
+t3con_tmr3on = 1 -- 1 = enables timer 3
+pir2_tmr3if = off -- clear overflow to start timer
+
+-- set timer3 clock prescaler
+t3con_t3ckps = 1 -- set prscal of 1:2
+
+-- define a rollover of 1 second
+-- holds 1 second: 1.00000000000 or 0x174876E800
+var byte*6 one_sec
+var byte one_sec_array[6] at one_sec
+one_sec_array[5] = 0x00
+one_sec_array[4] = 0x17
+one_sec_array[3] = 0x48
+one_sec_array[2] = 0x76
+one_sec_array[1] = 0xE8
+one_sec_array[0] = 0x00
+
+-- counter will roll over 38.14697265625 times in one second for 20mhz
clock
+-- (1sec / ( (timer freq ) * clock increments ) / prescaller 1:2 =
interrupts per sec
+-- (1 / ( (1/20_000_000*4) * 65536 ) / 2 =
38.14697265625
+-- holds 0.14697265625 or 36C0679D9 (the remainder)
+var byte*6 num_add
+var byte num_add_array[6] at num_add
+num_add_array[5] = 0x00
+num_add_array[4] = 0x03
+num_add_array[3] = 0x6c
+num_add_array[2] = 0x06
+num_add_array[1] = 0x79
+num_add_array[0] = 0xD9
+
+-- counts the remainder up to one second
+-- after count is > 1 second, we will minus 1 second within interrupt.
+var byte*6 remainder_count = 0
+var byte remainder_count_array[6] at remainder_count
+
+-- seconds counter, allow it to roll over to 0
+var byte second_count = 255
+-----------
+
+var byte count1 = 0 -- counts up to 38 (interupt every 38.14697265625 sec)
+procedure timer_isr() is
+ pragma interrupt -- interupt procedure
+
+ if !PIR2_TMR3IF then -- check if this is a timer3 interupt
+ return -- exit interupt if it is not
+ end if
+
+ PIR2_TMR3IF = off -- clear timer overflow
+
+ count1 = count1 + 1 -- count the number of times an interrupt
occurs
+ if count1 == 38 then -- if timer is at 1 sec
+
+ -- if remainder_count is > 1 sec
+ if remainder_count > one_sec then
+
+ -- remove one second from remainder_count
+ remainder_count = remainder_count - one_sec
+
+ -- remove one second from actual timing
+ count1 = count1 + 1
+ else
+ -- add 0.14697265625 (the remainder) to remainder_count
+ remainder_count = remainder_count + num_add
+ end if
+
+ second_count = second_count + 1 -- increment the seconds
+ if second_count == 60 then -- reset seconds to 0 each min
+ second_count = 0
+ end if
+
+ -- send seconds to serial port
+ print_byte_dec (serial_hw_data,second_count)
+ serial_hw_data = 0x0D
+ serial_hw_data = 0x0A
+
+ led = !led -- switch led on/off each second
+ count1 = 0
+ end if
+end procedure
+
+-- main program here
+forever loop
+end loop
+
--
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