Author: sebastien.lelong
Date: Wed Jan 7 11:43:23 2009
New Revision: 732
Added:
trunk/sample/by_device/16f77/16f77_adc_lowres.jal
Modified:
trunk/include/peripheral/adc/adc_hardware.jal
Log:
issue 31: support for 8-bits only ADC PIC + sample for 16f77
Modified: trunk/include/peripheral/adc/adc_hardware.jal
==============================================================================
--- trunk/include/peripheral/adc/adc_hardware.jal (original)
+++ trunk/include/peripheral/adc/adc_hardware.jal Wed Jan 7 11:43:23 2009
@@ -57,6 +57,11 @@
include delay
+-- sanity check
+if adc_hardware_high_resolution & ! defined(ADRESH) then
+ pragma error -- This pic does not seem to handle 10-bits ADC
+end if
+
-- local variables
var volatile byte _adcon0_shadow = 0
@@ -74,8 +79,17 @@
delay_10us(_adc_acquisition_time) -- wait acquisition time
ADCON0_GO = true -- start conversion
while ADCON0_GO loop end loop -- wait till conversion
finished
- adc_byte = ADRESH -- read high byte
- -- (low resolution is left
justified !!
+ -- 2 cases:
+ -- - PIC has 10-bits ADC: since low resoltion if left
+ -- justified, need to read ADRESH
+ -- - PIC has only a 8-bits ADC: don't bother consider
+ -- justification, there's only one ADC register
+ if defined(ADRESH) == true then
+ adc_byte = ADRESH -- read high byte
+ -- (low resolution is left
justified !!
+ else
+ adc_byte = ADRES
+ end if
if target_clock <= (5_000_000 / 16) then
delay_10us(1) -- to satisfy 2*Tad for next
conversion
end if
@@ -124,7 +138,7 @@
if ! adc_hardware_high_resolution then
_adc_read_low_res(adc_chan,adc_value)
else
- _adc_read_low_res (adc_chan,adc_hbyte)
+ _adc_read_low_res(adc_chan,adc_hbyte)
adc_value = ADRESL
-- shift the 2 highest order bits form high byte to low byte
asm rrf adc_hbyte,f
Added: trunk/sample/by_device/16f77/16f77_adc_lowres.jal
==============================================================================
--- (empty file)
+++ trunk/sample/by_device/16f77/16f77_adc_lowres.jal Wed Jan 7 11:43:23
2009
@@ -0,0 +1,86 @@
+-- Title: Sample showing how to use adc_hardware library
+-- Author: Sebastien Lelong, Copyright (c) 2008-2009, all rights reserved.
+-- Adapted-by:
+-- Compiler: >=2.4i
+--
+-- This file is part of jallib (http://jallib.googlecode.com)
+-- Released under the BSD license
(http://www.opensource.org/licenses/bsd-license.php)
+--
+-- Description: this program shows how to use adc_hardware library. It
regurlarly performs an
+-- Analog-to-Digital Conversion, on channel AN0 and sends the result
through serial.
+--
+-- Notes: as output, this sample produces characters on a serial link, and
uses delay library.
+-- First be sure you're able to run serial and delay tests.
+--
+--
+-- Few words about diagram: this program performs ADC on channel AN0, so
you can
+-- any voltage source connected to AN0 (no more 5V please). To test the
whole, you can
+-- use a voltage divider:
+--
+-- 5V
+-- |
+-- Z
+-- Z R1 -----------
+-- Z |
+-- |------ AN0-| PIC
+-- Z |
+-- Z R2 |
+-- Z
+-- |
+-- GND
+--
+--
+-- - R1=1K, R2=1K: you should get ~127 as ADC value
+-- - R1=1K, R2=2.2K: you should get ~175 as ADC value
+--
+
+-- select chip
+include 16f77
+-- set all IO as digital, will turn ADC on later (by adc lib)
+enable_digital_io()
+
+-- We'll use internal oscillator. It work @ 8MHz
+pragma target CLOCK 20_000_000
+pragma target OSC HS
+-- Specify no postscaler, ie. really runs @8MHz
+-- no watchdog, please
+pragma target WDT disabled
+
+include delay
+-- ok, now setup serial
+const usart_hw_serial = true -- true = RS232, false = SPI
+const serial_hw_baudrate = 19_200
+include serial_hardware
+serial_hw_init()
+-- inform user PIC is ready !
+serial_hw_write("!")
+
+-- Configure ADC
+-- We just need only one ADC channel
+const adc_hardware_nchan = 1
+-- We won't use any external VRef, so measures are done
+-- according to PIC powering voltage
+const adc_hardware_nvref = 0
+-- The maximum resistance while measuring ADC is... (unit: ohms)
+-- Being accurate helps speeding up ADC acquisition
+const adc_hardware_rsource = 2_000
+-- In this example, we'll perform low resolution ADC: results are
+-- coded on 8bits
+const adc_hardware_high_resolution = false
+-- Now include the famous library
+include adc_hardware
+-- And initialize the whole with our parameters
+adc_init()
+
+
+-- will periodically send those chars
+var byte measure
+forever loop
+ -- get ADC result, on channel 0
+ measure = adc_read_low_res(0)
+ -- send it back through serial
+ serial_hw_write(measure)
+ -- and sleep a litte...
+ delay_1ms(200)
+end loop
+
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