On Fri, 2004-11-19 at 05:56, calin_dorohoi wrote:
> I have to interface with:
> 
> 1. An IR sensor.
> 2. An alphanumerical LCD display.
> 3. An IDE bus.

One of my projects requires some interfacing on the CompactFlash bus,
which can run either 3V3 or 5V depending on the host... So we use a
little level translator... the SN74LVCC3245. This little bugger will is
bidirectional and allows you to force the local bus side to one voltage,
and allow the bus on the "outside world" side to go to a different
logic
level...

Just in case the series I limiting resistors don't work for your
particular IDE bus...

Dave

My reply was in response to an enquiry regarding an LCD, hence 470R is 
fine, even if you do use the busy flag, which I don't. If you read a few 
other posts I've made on the subject you'll find that I generally
don't 
mix 3V and 5V circuits, since everything I need, with a couple of sensor 
exceptions, is available in 3V. In addition, if you look back on the 
posts regarding 5V supplied to the micro you'll find that as far as can 
be discerned (ie it may shorten the life from 10 years to 9 years) by 
the many people who have done this, powering the micro from 5V, or even 
applying 5V to the I/O pins doesn't seem to have any lasting effect.

Obviously I don't recommend this. When I answer I answer from my own 
experiences and evaluations. I try to quote the specs, as I did in this 
post, but I believe that Ti are over conservative in many areas. The 
most glaring being the 3V6 spec for 8MHz.

I have a minimum of 16 designs in the field using MSP430s with an 
average of 2000 units per design. all but a couple of the designs have a 
5V LCD on them. Most of the designs were done before December 2000 (all 
but 4). I have not had a single PCB retunred with a failure. (software 
or hardware) From this I can only assume that I am doing something right.

Al

Matthias Weingart wrote:
> On Sun, Nov 21, 2004 at 03:19:33PM +1030, onestone wrote:
> 
> 
>>Most of the Ti samples use 330R but I still use 470R. Theoretically this

>>may not be considered adequate, since you need to drop 1.7V, and the 
>>protection diodes are rated at 2mA, thus you need around 750R, but
I've 
>>never had a problem, and find this a good compromise.
> 
> 
> 470R? This really works? The 3.5mA are able to rise the power supply
> of the MSP430 above the 4.2volts allowed if it runs at low current (1uA)
> and the 5V-output will stay at high for a long time. I would use 10k-100k
> (but dont expect high speed).
> 
> In case of dot matrix LCD's this is not a problem. Only the databus is
> a output and only for short time (reading busy flag).
> 
> M.
> 
> 
> 
> .
> 
>  
> Yahoo! Groups Links
> 
> 
> 
>  
> 
> 
> 
> 

On Sun, Nov 21, 2004 at 03:19:33PM +1030, onestone wrote:

> Most of the Ti samples use 330R but I still use
470R. Theoretically this 
> may not be considered adequate, since you need to drop 1.7V, and the 
> protection diodes are rated at 2mA, thus you need around 750R, but
I've 
> never had a problem, and find this a good compromise.

470R? This really works? The 3.5mA are able to rise the power supply
of the MSP430 above the 4.2volts allowed if it runs at low current (1uA)
and the 5V-output will stay at high for a long time. I would use 10k-100k
(but dont expect high speed).

In case of dot matrix LCD's this is not a problem. Only the databus is
a output and only for short time (reading busy flag).

M.

Most of the Ti samples use 330R but I still use 470R. Theoretically this 
may not be considered adequate, since you need to drop 1.7V, and the 
protection diodes are rated at 2mA, thus you need around 750R, but I've 
never had a problem, and find this a good compromise.

Al

Jack wrote:

> 
> Al,, what value resistance for MSP430 outputs to TTL inputs?
> I recall you mentioning 470 ohms to the gate of an FET, but
> not to TTL.
> 
> Jack
> 
> 
> --- In msp430@msp4..., onestone <onestone@b...> wrote:
> 
>>If you get really stuck email me. Up until I sourced these parts I ran 
>>all my displays on 5V, and just used current limiting resistors in the 
>>I/O lines. These systems run 24 hours a day, and there are thousands 
>>that have been running for 4 years now, so this is safe.
>>
>>Al
> 
> 
> 
> 
> 
> 
> 
> 
> .
> 
>  
> Yahoo! Groups Links
> 
> 
> 
>  
> 
> 
> 
> 

Al,, what value resistance for MSP430 outputs to TTL inputs?
I recall you mentioning 470 ohms to the gate of an FET, but
not to TTL.

Jack


--- In msp430@msp4..., onestone <onestone@b...> wrote:
> If you get really stuck email me. Up until I
sourced these parts I ran 
> all my displays on 5V, and just used current limiting resistors in the 
> I/O lines. These systems run 24 hours a day, and there are thousands 
> that have been running for 4 years now, so this is safe.
> 
> Al

If you get really stuck email me. Up until I sourced these parts I ran 
all my displays on 5V, and just used current limiting resistors in the 
I/O lines. These systems run 24 hours a day, and there are thousands 
that have been running for 4 years now, so this is safe.

Al

Omer YALHI wrote:

> Al thank you for the input.  I am interested in
converting a project from
> PIC18F452 to MSP430F449 which uses 20x4 character LCD (5V).  I'll
email them
> and see what happens.
>  
> Regards, Omer
> 
> 
>   _____  
> 
> From: onestone [mailto:onestone@ones...] 
> Sent: Saturday, November 20, 2004 12:55 AM
> To: msp430@msp4...
> Subject: Re: [msp430] Re: How to interface MSP430 chips with 5V devices?
> 
> 
> Hi Omer, yes they are compatible with HD44780. Very good devices. I also 
> use their mono graphic and colour gaphic panels. The particular model of 
> character unit I use is WH2004D-TMI-ET 20 x 4 small format LED backlit. 
> You may pay a little more than $5. I buy mine through a german friend 
> who lives and travels extensively around Asia. He buys in 100 lots. 
> Although I only bought 10 of these last time. I think the lady he talks 
> to is julie. The graphics displays have built in negative contrast 
> voltage supplies. Very useful. They have a pot on board, so add an NTC 
> and you have simple temperature compensated contrast.
> 
> If you don't have any success let me know and I'll see if I can
make 
> contact for you.
> 
> Al
> 
> 
> 
> 
> 
> 
> 
> 
> .
> 
>  
> Yahoo! Groups Links
> 
> 
> 
>  
> 
> 
> 
> 

Al thank you for the input.  I am interested in converting a project from
PIC18F452 to MSP430F449 which uses 20x4 character LCD (5V).  I'll email
them
and see what happens.
 
Regards, Omer


  _____  

From: onestone [mailto:onestone@ones...] 
Sent: Saturday, November 20, 2004 12:55 AM
To: msp430@msp4...
Subject: Re: [msp430] Re: How to interface MSP430 chips with 5V devices?


Hi Omer, yes they are compatible with HD44780. Very good devices. I also 
use their mono graphic and colour gaphic panels. The particular model of 
character unit I use is WH2004D-TMI-ET 20 x 4 small format LED backlit. 
You may pay a little more than $5. I buy mine through a german friend 
who lives and travels extensively around Asia. He buys in 100 lots. 
Although I only bought 10 of these last time. I think the lady he talks 
to is julie. The graphics displays have built in negative contrast 
voltage supplies. Very useful. They have a pot on board, so add an NTC 
and you have simple temperature compensated contrast.

If you don't have any success let me know and I'll see if I can make 
contact for you.

Al

I use the WG320240C, which I pay US$66.70 for in low volume (like 10). I 
don't have prices for the others. I didn't pay for the two colour
panels 
I have, they were samples from the last Taiwan show. I don't know how 
this compares for you, but it is a third the price the local disti used 
to charge for the Hyundai part, and well under half any other quote for 
low volumes.

Al

Alex Holden wrote:

> onestone wrote:
> 
>>Alex I buy in very small quantities. Even the guy I buy through often 
>>just orders 20 - 50 at a time. They are very lacking (like many 
>>Taiwanese companies), in hard technical data, but the interface is basic

>>HD44780. The Graphics displays are nice. I use the 320x240 with built in

>>SED1335 and contrast voltage supply, with 3V Vcc. I simply swapped it 
>>for an old Hyundai 256 x 128 HY25501G, modifed the timing registers to 
>>suit and off I went. But be aware the contrast changes markedly as you 
>>enable more row drivers. ie it will actually display as a 256 x 128 
>>display, although skewed, but when you change the framing the image 
>>disappears. It is simply Vo load changing.
> 
> 
> Sounds good. The one I'm interested in is the WX320240C (320x240
pixels, 
> 94.7mm x 71.7mm, with SED1335). The displays I've found before this
one 
> have all been physically too big for my app, too low resolution 
> (128x64), or weren't available in small quantities. Roughly how much
are 
> you paying for the 320x240 displays if you don't mind me asking?
> 

onestone wrote:
> Alex I buy in very small quantities. Even the guy
I buy through often 
> just orders 20 - 50 at a time. They are very lacking (like many 
> Taiwanese companies), in hard technical data, but the interface is basic 
> HD44780. The Graphics displays are nice. I use the 320x240 with built in 
> SED1335 and contrast voltage supply, with 3V Vcc. I simply swapped it 
> for an old Hyundai 256 x 128 HY25501G, modifed the timing registers to 
> suit and off I went. But be aware the contrast changes markedly as you 
> enable more row drivers. ie it will actually display as a 256 x 128 
> display, although skewed, but when you change the framing the image 
> disappears. It is simply Vo load changing.

Sounds good. The one I'm interested in is the WX320240C (320x240 pixels, 
94.7mm x 71.7mm, with SED1335). The displays I've found before this one 
have all been physically too big for my app, too low resolution 
(128x64), or weren't available in small quantities. Roughly how much are 
you paying for the 320x240 displays if you don't mind me asking?

-- 
------------ Alex Holden - http://www.linuxhacker.org ------------
If it doesn't work, you're not hitting it with a big enough hammer

Alex I buy in very small quantities. Even the guy I buy through often 
just orders 20 - 50 at a time. They are very lacking (like many 
Taiwanese companies), in hard technical data, but the interface is basic 
HD44780. The Graphics displays are nice. I use the 320x240 with built in 
SED1335 and contrast voltage supply, with 3V Vcc. I simply swapped it 
for an old Hyundai 256 x 128 HY25501G, modifed the timing registers to 
suit and off I went. But be aware the contrast changes markedly as you 
enable more row drivers. ie it will actually display as a 256 x 128 
display, although skewed, but when you change the framing the image 
disappears. It is simply Vo load changing.

Al

Alex Holden wrote:

> Omer YALHI wrote:
> 
>>Sorry to barge in, but I was interested to see that there is in fact 3V
LCD
>>character modules and immediately checked out their site.  I could not
find
>>any info where to get them, can I order them online somewhere for test
>>purposes?  Are they HD44780 based?
> 
> 
> I also just had a look at their site and one of their graphics displays 
> sounds ideal for an upcoming project of mine. I've sent them an email 
> asking about availability and prices etc. Hopefully they're not
another 
> one of those suppliers who won't sell less than several hundred at a
time...
>