Serial LCD - quick question

[MikeGyver]

Quick question. Will this serial LCD work with picaxe?
20M overclocked to 8mhz (setfreq m8)

http://www.sparkfun.com/commerce/product_info.php?products_id=812

I guess this is the part that I want to make sure about before I buy.
"9600bps TTL serial (do not attach directly to RS232 port)"

 

[ciseco]

(Should) do yes

Miles
________
marijuana joint

 

[westaust55]

Please have a look at manual 2 page 151 (latest version)

There is a table which gives the predefined "word" to use with the SEROUT command for each PICAXE speed 4/8/16MHz to achieve the required baud rate.

in your case, SEROUT pin, N9600_8, (info you want to sent)

 

[hippy]

"9600bps TTL serial (do not attach directly to RS232 port)"

In short that's saying don't put +12V or negative voltages into it.

 

[Dave E]

Now I am a bit confused. I don't mean to highjack this thread, but this is along the same line:

I normally use an LCD that has 3 baud rate choices: 2400, 9600 and 19,200.
I normally run 2400. In my code, I use SEROUT pin, T2400, (data_to_send). I do not include the _4 part in T2400_4. Do I need to? Is the communication more reliable or affected in any way if I do/do not use _4? The example in the manual does not use it; Manual 2 page 152.

Also, I am working with an 18X and decided to try something. I wanted to communicate with the LCD at a higher rate but the 18X does not support 9600 or 19200 baud but I set the LCD to 9600 baud and in my code I used SEROUT pin, T4800, (data) and set the frequency to 8 MHz (setfreq m8). It worked. I am now running the 18X at 8MHz communicating with the LCD at 9600 baud. Should this work? Is this a fluke with my particular LCD or is this OK. I assume that what is happening is that the T4800 command assumes 4MHz and I am just doubling the actual frequency by running at 8MHz.

CORRECTION:
I tried something.
The 18X does support 9600 baud but you must use T9600_8. So I guess I answered my own question. Not using the _4 or _8 does seem to cause a default to 4MHz.

Again, I did not mean to highjack but thought this info was related and may be helpful.

Comments welcome.

Dave E

 

[Technical]

T4800, T4800_4, T9600_8 are actually all the same setting.

However the _4 and _8 suffix are designed to help people remember which baud rate is really occuring at different resonator speeds (4 and 8 MHz) - a 4800 baud rate at double speed becomes 9600. Of course you have to match the suffix to the actual frequency you are using at that point.

 

[Dave E]

Thanks Tech.
That answers that.

Dave E

 

[westaust55]

As an extension of what Techncial has stated,

the "words" T2400, T4800, T9600_8, etc are effectively pre-defined symbols

its is as if you added lines like these to your program

SYMBOL T2400 = 0
SYMBOL T4800 = 3
SYMBOL T9600_8 = 3

If you run a program like this:

b0 = T2400
b1 = T4800
b2 = T9600_8
SEROUT 7, N2400, (#b0,",",#b1,",",#b2)

you can see the values.