| Author |
Message |
Help
Joined: 15 Feb 2005
Posts: 560
Helped: 4
|
 15 Dec 2007 4:22 led txd on rs232 |
|
|
|
|
Hi,
Is it possible without MCU directly using RS232 to control some output device?
At this moment i just only need to control one LED and one Buzzer.
Thank you.
|
|
| Back to top |
|
 |
IanP
Joined: 05 Oct 2004
Posts: 6490
Helped: 1542
Location: West Coast
|
15 Dec 2007 5:31 picaxe toronto |
|
|
|
|
This may do things rather difficult ..
You see, information is usually coded in numbers and not in the presence or absence of a signal ..
And to “decode” a serially sent byte one needs some “intelligence” which is easily provided by even reduced-pin microcontroller ..
For simple tasks like you just mentioned in your post I would go for a simple 8-pin microcontroller, programmable in simple basic and with built-in serial interface and clock, so, in fact, only this 8-pin “gizmo” + one, or two BJTs (MOSFETS) will be your hardware ..
What I have in mind is the PICAXE-08, but the same can be done, as you know, with any other MCU ..
Regards,
IanP
|
|
| Back to top |
|
|
blueroomelectronics
Joined: 17 Sep 2006
Posts: 1681
Helped: 99
Location: Toronto, Canada
|
15 Dec 2007 5:55 rs232 control led |
|
|
|
|
| I would say yes, you can toggle the DTR, CTS lines and hook an LED and buzzer to each. Might need a small driver transistor though.
|
|
| Back to top |
|
|
Help
Joined: 15 Feb 2005
Posts: 560
Helped: 4
|
15 Dec 2007 7:21 Re: RS232 Control LED without MCU |
|
|
|
|
Hi IanP,
Thank for your advice. I'm not familiar with the PIC. I'm using 8052 MCU. there is no tiny MCU for 8052 with 8-pin.
I just need to 2 output signal. So, hope can design a very simple and no costly design and i just only have serial port TXD and RXD pin only.
Thank You.
Hi blueroomelectronics,
If i just have the TXD and RXD? Is it any possibility to do it? I had seen other people did before, they had using MAX232 as a driver to control 2 output but i'm not sure whether their thing is work fine not.
Thank you.
|
|
| Back to top |
|
|
Google
AdSense
|
15 Dec 2007 7:21 Ads |
|
|
|
|
|
|
| Back to top |
|
|
IanP
Joined: 05 Oct 2004
Posts: 6490
Helped: 1542
Location: West Coast
|
15 Dec 2007 8:43 Re: RS232 Control LED without MCU |
|
|
|
|
The 8051 is really weak on the 8 pin side of things ..
The king of the hill of 8 pin Micro's is the PIC 16F508, but, based on similar chip, there is the PICAXE – family, with the PICAXE-08 being its 8-pin member ..
The PICAXE-family is only based on PICs, but the programming language is BASIC, so if you know just a little bit of BASIC you can easily switch to PICAXE ..
On top of that, PICAXE is programmable directly through serial port (3-wire) ..
Here is an example of PICAXE-based receiver that sets/resets pins after receiving simple commands through 3-wire (Tx, Rx and GND) serial port:
http://www.edaboard.com/viewtopic.php?t=187850
That’s really very tempting option ..
Otherwise, should this be done on 8051, there is the 89C2051, or LPC764 .., but all of them require special programmer, or an adaptor that reduces 40-pin standard 8051 to 20-pin 2051 ..
Regards,
IanP
| Code: |
180R
.---. .------. .---------------.
/ | .------. .----. .----| |---. | |
GND | O |--5------. .----| ===| 1 | O |----------' `------' `--| Digital Out |
| O | | | | .----| | || .------. | |
| O | .---|---|----| | ===| 2 | O ||----------.----| |------| Digital In |
| O | | | | | `----| | || | `------' | |
TX | O |--3--' `---|----| ===| 3 | O |---. _|_ 22K .--| 0v |
| O | | `------' `----' | | | | | |
RX | O |--2----------' | | | 10K | `---------------'
| O | | | | | PICAXE
| O | | `-.-' |
\ | 9-Way Female | | |
`---' Socket (DCE) --^------^---------------^-- 0v
|
|
|
| Back to top |
|
|
