capture/repeat data ?

[Sam]

Hi All,

DynamoBen,thanks to this forum I've started learning to program serial into the PIC !

Here is the code I'm using: (forgot how to do the code quote here)

'12F675
_CONFIG
_INTRC
_NOCLKOUT
_WDT_ON
_PWRTE_ON
_MCLRE_OFF
_BODEN_ON
DEFINE OSCCAL_1K 1
INCLUDE "modedefs.bas"
TX_Pin VAR GPIO.0 'To DB9 RX pin 2
RX_Pin VAR GPIO.1 'To DB9 TX pin 3

TRISIO.0 = 0 'Set GPIO.0 to output.
TRISIO.1 = 1 'Set GPIO.1 to input

ANSEL = 0 'disable ADCs
CMCON = 7 'disable comparator

AChar VAR BYTE
tx_pin = 0 'inverted mode idle state

achar="A"
Pause 100 'OSC settle time...

loop:
SerOut tx_pin,N9600,["AT SH 6A C2 00 ",13,10] 'set header
Pause 2000
SerOut tx_pin,N9600,["85 00",13,10] 'fold mirrors in


Problem is the elm322 and the vehicle does not respond at all. I've tried sending inverted and non inverted but the data light on the elm never activates as it does when I send this same data to the vehicle with the laptop.

Do I need to use a MAX232 for this or maybe modify the elm circuit as talked about in the elm docs ?

I can read it all in hyperterminal fine, any advice and guidance is much appreciated.

[DynamoBen]

You don't need a max232. First thing to check is that Tx and Rx are crossed over. TX to RX and RX to TX. That would be enough to cause your problem.

Also on page 17 of the datasheet it talks about about RX input being inverted based on the TTL standard. You would need to reinvert this line for this to work properly. This can be done via software or hardware.

Let me know what you find.

[Sam]

Hey Ben,
You were right, I had to switch the serial output of the PIC from the 2 pin on the DB9 cable to the 3 pin. But, that still didn't work so I then removed the 1k resistor that I had inline btwn the PIC and the DB9 and directly connected it to the 3 pin of the DB9 and it worked perfectly!

Now I have to learn SERIN,the code I posted actually came from a post from Mister_e because it seemed perfect for my project (thank you Mister_e) and then I just changed the output data. But, when I try to send anything from hyperterminal to the 12F675 nothing happens,nothing in the terminal window will show up regardless of any key I press???

Here is the actual code from Mister_e's post that I need help with getting the SERIN part working if anyone has some suggestions on why it's not working for me.



'12F675
@ __CONFIG _INTRC_OSC_NOCLKOUT & _WDT_ON & _PWRTE_ON & _MCLRE_OFF & _BODEN_ON
DEFINE OSCCAL_1K 1
INCLUDE "modedefs.bas"
TX_Pin var GPIO.0 'To DB9 RX pin 2
RX_Pin var GPIO.1 'To DB9 TX pin 3

TRISIO.0 = 0 'Set GPIO.0 to output.
TRISIO.1 = 1 'Set GPIO.1 to input

ANSEL = 0 'disable ADCs
CMCON = 7 'disable comparator

AChar var byte
tx_pin = 0 'inverted mode idle state

achar="A"
Pause 100 'OSC settle time...

loop:
SerOut tx_pin,N2400,["Waiting for ",achar,13,10]
SERIN rx_pin,N2400,[achar]
serout tx_pin,N2400,["Got it...",13,10]
goto loop


Thanks again, this is great!

[DynamoBen]

When you communicate with a PC you are now working with RS232 which requires a MAX232 or other circuitry to convert to TTL (the elm devices uses that circuitry for serial in/out). However, with the elm device you are talking TTL and can connect directly to a pic. BTW you can eliminate all the serial circuitry between the elm and pic (you will still need to flip Rx in software or add circuitry to do it via hardware).

[Sam]

Please check out this thread: http://www.picbasic.co.uk/forum/show...=hyperterminal

This is where I found the code I'm trying and they say a MAX232 isn't needed and I can read the data from the 12F675 in hyperterminal with only a 1k resistor in line with pin 2 direct to the pc which is running hyperterminal.

However, I cannot get anything to show up in hyperterminal when I try typing on that pc. Nothing that I type shows in the hyperterminal window regardless if the DB9 is connected to the 12F675 or not. This is the same pc that I've used to communicate with the elm322 and when doing that,I'm able to enter characters in the h/t window.

I'm certainly not doubting your previous statement at all but the guys in the thread above seem to have it working without a MAX232 chip so I thought it would work with my pc (laptop).

[DynamoBen]

The reason you see what you’re typing with the elm chip is because it is echoing the characters you’re typing.

In HyperTerm under Properties, there is a Settings tab. Under that there is ASCII Setup button and a check box that says Echo Typed Characters Locally. Check that box and try it again.

[mister_e]

AND there's some chance it don't work as their internal OSC is sometime pretty poor. You may need to calibrate it AND/OR using the DEFINE OSCCAL_1K 1

DEBUG is recommended for those nifty PIC.