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Hi,
I was wondering if it would be possible to use PortA as analog but
use 1 pin as digital output ?
So:
RA0-RA3 analog 10bit
RA4 digital output
RA5 analog input 10bit
Can anyone help me with the ADCON settings ?
Further RE0-RE2 will be digital output
thanks
Learning everyday
Hi RF,
Since RA4 is not an analog pin you get it as digital at default.
Then, the rest is as you needed. See the table below.
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RE0-RE2 meaning that AN5, AN6 and AN7 are needed as digital in your case.
Thus, you endup with
ADCON1.0=0
ADCON1.1=1
ADCON1.2=0
ADCON1.3=0
ADCON1.4=0 'ignore
ADCON1.5=0 'ignore
Then, assuming you want to use RC OSC,
ADCON1.6=0 '(here you should use DEFINE)
Then, you need 10-bit res.,
ADCON1.7=1 'right justified is needed with 10-bit. Left justified is needed with 8-bit.
You are set.
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Edit: Don't forget to set your TRIS registers for input/output thingie.
Hi Sayzer,
It is working, thanks I start to understand the ADCON setting
Can you point me how Tris and internal pull-up works on a 877 ?
Sure.
TRISA = %00100000
Sets PORTA.5 as an input pin and all others in PORTA as output pin.
There is something here to pay attention for.
Although PORTA is 6-bit (RA0 to RA5), TRIS register uses 8-bit (0 to 7).
In this case, only right bits are considered. Thus, Bit7 and Bit6 in TRISA register are ignored ; whether they are 1 or 0 it won't matter.
TRISE = %00000000
Sets PORTE.0, PORTE.1 and PORTE.2 as output pins.
Also here, PORTE is only 3-bit (RE0 to RE2). So that, all other bits in TRISE register will be ignored.
You can also set an individual bit by,
TRISE.0=0
Sets RE0 as an output pin.
or
TRISE.0=1 sets RE0 as an input pin.
If you set a pin as analog, it must be an input pin.
For Internal Weak Pull-ups, there is a bit in OPTION_REG register.
Bit7.
OPTION_REG.7 is PORTB Pull-up Enable bit
OPTION_REG.7 = 1
PORTB pull-ups are disabled.
OPTION_REG.7 = 0
PORTB pull-ups are enabled by individual port latch values.
Once you set this bit as 0 then you can have weak pull ups on PORTB pins that were set to be input pins beforehand.
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Ok fine,
Understood, so PORTB has only the weak pull-up feature ?
another question concerning HSERIN
I'm using a 16f877 with max 232 at 4mhz
I'm having problems reading multiple variables in 1 serin string
It works, but after some times it hangs so I think there is a buffer overflow
What worries me is that when i measure with an osciloscope, there are pulses on portc.7 the UART RX even with no max232 chip connected ???
Here is a part of the code:
DEFINE HSER_RCSTA 90h ' enable serial port,
' enable continuous receive
'
define HSER_TXSTA 24h ' enable transmit,
' BRGH=1
'
define HSER_SPBRG 103 ' set baudrate to 2400
DEFINE HSER_CLOERR 1 ' automatic clear overrun error
TRISB = %00000000
'OPTION_REG.7 = 0 ' Enable PORTB pullups
TRISC = %10000000
TRISD = %00001111
TRISE = %000
loop:
Hserin 500,LCD,[wait ("TAR"),dec3 var1,wait ("ANT"),DEC3 var2,wait ("AUX"),DEC3 var3,wait ("EXT"),DEC3 var4]
LCD:
pause 10
Lcdout $fe, 1 ' Clear screen
Lcdout "VAR1: ",#VAR1," VAR2: ",#var2
Lcdout $fe, $c0, "VAR3: ",#VAR3," VAR4:",#VAR4
Goto loop
Any Idea ?
Hi RF,
I do not have much experience in serin/serout commands.
I may mislead you with some incorrect or never tried advices.
But, at first look, I am not sure whether you can use more then one "WAIT" in one serin command or not.
I believe another member with valuable and reliable Serin/Serout experiences will respond.
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Hi,
I just found this thread as I was looking at how to set up 4 of the 13 availiable A2D converter pins on my 18F4620. Can someone clarrify for me......
If I want to set up AN0, AN1, AN4 & AN12 (8 bit resolution only) and leave every other pin on PORTA & B as digital input/ouputs.....
is this code correct?
ADCON1.0=0
ADCON1.1=0
ADCON1.4=0
ADCON1.12=0
'tristates will already be defined above