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Discussion Groups | Rabbit-Semi | Motherboard PCB Design for RCM3000 Question
This is a group for folks designing and programming embedded systems using the Rabbit Semiconductor C-programmable microcontroller. Rabbit Semi is a spin-off from Z-World who makes a variety of embedded modules and tools. This group is not affiliated with either Rabbit or Z-World, but is a user forum for sharing ideas, asking questions, flaunting knowledge, and other typical user group stuff. The Rabbit is a powerful uC, supported by a full-featured C-compiler.
Motherboard PCB Design for RCM3000 Question - Jonathan Loechel - Oct 3 0:14:17 2008
Hi, Im designing a motherboard PCB for the RCM3000 to plug into as part of a university
poject.
I just want to check that what I am doing is correct.
I am planning to set the pins on the parallel ports that I am not using (all of B, D, and E and half of F and half of G) as output pins and then leave them floating on the PCB. Is this correct??
Im also unsure of what to do with the Port A pins. I want to be able to use the programming connector to reprogram the RCM3000 while it's on the motherboard, but I also want it to run normally when the programming cable is unplugged. Do I leave the port A pins floating, grounded, tied high ???
I've read through the datasheet and the prototyping board schematic, and the application notes but cant come up with a definative answer.
If anyone can help, that would be great. Thanks.
Jon.
Make the switch to the world's best email. Get Yahoo!7 Mail! http://au.yahoo.com/y7mail
(You need to be a member of rabbit-semi -- send a blank email to rabbit-semi-subscribe@yahoogroups.com )
I just want to check that what I am doing is correct.
I am planning to set the pins on the parallel ports that I am not using (all of B, D, and E and half of F and half of G) as output pins and then leave them floating on the PCB. Is this correct??
Im also unsure of what to do with the Port A pins. I want to be able to use the programming connector to reprogram the RCM3000 while it's on the motherboard, but I also want it to run normally when the programming cable is unplugged. Do I leave the port A pins floating, grounded, tied high ???
I've read through the datasheet and the prototyping board schematic, and the application notes but cant come up with a definative answer.
If anyone can help, that would be great. Thanks.
Jon.
Make the switch to the world's best email. Get Yahoo!7 Mail! http://au.yahoo.com/y7mail
(You need to be a member of rabbit-semi -- send a blank email to rabbit-semi-subscribe@yahoogroups.com )
RE: Motherboard PCB Design for RCM3000 Question - "Fournier, Pete" - Oct 3 8:07:44 2008
Jon,
If the parallel ports are not doing anything you don't need to set them
to anything. If you have the space, you should make provisions on your
motherboard to allow easy access to all the I/O even if it is just for
troubleshooting.
>I'm also unsure of what to do with the Port A pins.
Do you mean parallel port A or serial port A?
Parallel port A has nothing to do with programming.
If you have the space you might want to bring the programming port to
the motherboard, add a program/debug toggle switch, add the circuit that
is on the programming cable and bring it to an external DB9 to make it
easy the reprogram with a standard serial port cable. Samtec makes the
connector/cable. You might be able to get samples.
If you do nothing else, add a program/debug toggle switch to your
programming cable, it takes a LOT of stress off the cable and connector.
-Pete
________________________________
From: r...@yahoogroups.com [mailto:r...@yahoogroups.com]
On Behalf Of Jonathan Loechel
Sent: Thursday, October 02, 2008 9:12 PM
To: r...@yahoogroups.com
Subject: [rabbit-semi] Motherboard PCB Design for RCM3000 Question
Hi, Im designing a motherboard PCB for the RCM3000 to plug into as part
of a university poject.
I just want to check that what I am doing is correct.
I am planning to set the pins on the parallel ports that I am not using
(all of B, D, and E and half of F and half of G) as output pins and then
leave them floating on the PCB. Is this correct??
Im also unsure of what to do with the Port A pins. I want to be able to
use the programming connector to reprogram the RCM3000 while it's on the
motherboard, but I also want it to run normally when the programming
cable is unplugged. Do I leave the port A pins floating, grounded, tied
high ???
I've read through the datasheet and the prototyping board schematic, and
the application notes but cant come up with a definative answer.
If anyone can help, that would be great. Thanks.
Jon.
________________________________
Make the switch to the world's best email. Get Yahoo!7 Mail
(You need to be a member of rabbit-semi -- send a blank email to rabbit-semi-subscribe@yahoogroups.com )
If the parallel ports are not doing anything you don't need to set them
to anything. If you have the space, you should make provisions on your
motherboard to allow easy access to all the I/O even if it is just for
troubleshooting.
>I'm also unsure of what to do with the Port A pins.
Do you mean parallel port A or serial port A?
Parallel port A has nothing to do with programming.
If you have the space you might want to bring the programming port to
the motherboard, add a program/debug toggle switch, add the circuit that
is on the programming cable and bring it to an external DB9 to make it
easy the reprogram with a standard serial port cable. Samtec makes the
connector/cable. You might be able to get samples.
If you do nothing else, add a program/debug toggle switch to your
programming cable, it takes a LOT of stress off the cable and connector.
-Pete
________________________________
From: r...@yahoogroups.com [mailto:r...@yahoogroups.com]
On Behalf Of Jonathan Loechel
Sent: Thursday, October 02, 2008 9:12 PM
To: r...@yahoogroups.com
Subject: [rabbit-semi] Motherboard PCB Design for RCM3000 Question
Hi, Im designing a motherboard PCB for the RCM3000 to plug into as part
of a university poject.
I just want to check that what I am doing is correct.
I am planning to set the pins on the parallel ports that I am not using
(all of B, D, and E and half of F and half of G) as output pins and then
leave them floating on the PCB. Is this correct??
Im also unsure of what to do with the Port A pins. I want to be able to
use the programming connector to reprogram the RCM3000 while it's on the
motherboard, but I also want it to run normally when the programming
cable is unplugged. Do I leave the port A pins floating, grounded, tied
high ???
I've read through the datasheet and the prototyping board schematic, and
the application notes but cant come up with a definative answer.
If anyone can help, that would be great. Thanks.
Jon.
________________________________
Make the switch to the world's best email. Get Yahoo!7 Mail
(You need to be a member of rabbit-semi -- send a blank email to rabbit-semi-subscribe@yahoogroups.com )
Re: Motherboard PCB Design for RCM3000 Question - Shawn Upton - Oct 4 21:55:01 2008
I've had no problems letting unused pins float on my applications.
Shawn Upton, KB1CKT
----- Original Message ----
From: Jonathan Loechel
To: r...@yahoogroups.com
Sent: Thursday, October 2, 2008 9:12:28 PM
Subject: [rabbit-semi] Motherboard PCB Design for RCM3000 Question
Hi, Im designing a motherboard PCB for the RCM3000 to plug into as part of a university poject.
I just want to check that what I am doing is correct.
I am planning to set the pins on the parallel ports that I am not using (all of B, D, and E and half of F and half of G) as output pins and then leave them floating on the PCB. Is this correct??
Im also unsure of what to do with the Port A pins. I want to be able to use the programming connector to reprogram the RCM3000 while it's on the motherboard, but I also want it to run normally when the programming cable is unplugged. Do I leave the port A pins floating, grounded, tied high ???
I've read through the datasheet and the prototyping board schematic, and the application notes but cant come up with a definative answer.
If anyone can help, that would be great. Thanks.
Jon.
(You need to be a member of rabbit-semi -- send a blank email to rabbit-semi-subscribe@yahoogroups.com )
Shawn Upton, KB1CKT
----- Original Message ----
From: Jonathan Loechel
To: r...@yahoogroups.com
Sent: Thursday, October 2, 2008 9:12:28 PM
Subject: [rabbit-semi] Motherboard PCB Design for RCM3000 Question
Hi, Im designing a motherboard PCB for the RCM3000 to plug into as part of a university poject.
I just want to check that what I am doing is correct.
I am planning to set the pins on the parallel ports that I am not using (all of B, D, and E and half of F and half of G) as output pins and then leave them floating on the PCB. Is this correct??
Im also unsure of what to do with the Port A pins. I want to be able to use the programming connector to reprogram the RCM3000 while it's on the motherboard, but I also want it to run normally when the programming cable is unplugged. Do I leave the port A pins floating, grounded, tied high ???
I've read through the datasheet and the prototyping board schematic, and the application notes but cant come up with a definative answer.
If anyone can help, that would be great. Thanks.
Jon.
(You need to be a member of rabbit-semi -- send a blank email to rabbit-semi-subscribe@yahoogroups.com )
Re: Motherboard PCB Design for RCM3000 Question - lwoodzw - Oct 6 13:22:55 2008
It's best not to let unused pins sit around as floating inputs, it's
possible for them to float to a mid-range voltage and cause
unnecessary current draw. Best option is leave them as inputs and tie
them high/low, or else make them outputs.
That said, I've never had problems with floating inputs either :v)
-Lynn
--- In r...@yahoogroups.com, Shawn Upton wrote:
>
> I've had no problems letting unused pins float on my applications.
>
> Shawn Upton, KB1CKT
>
> ----- Original Message ----
> From: Jonathan Loechel
> To: r...@yahoogroups.com
> Sent: Thursday, October 2, 2008 9:12:28 PM
> Subject: [rabbit-semi] Motherboard PCB Design for RCM3000 Question
> Hi, Im designing a motherboard PCB for the RCM3000 to plug into as
part of a university poject.
>
> I just want to check that what I am doing is correct.
> I am planning to set the pins on the parallel ports that I am not
using (all of B, D, and E and half of F and half of G) as output pins
and then leave them floating on the PCB. Is this correct??
>
> Im also unsure of what to do with the Port A pins. I want to be able
to use the programming connector to reprogram the RCM3000 while it's
on the motherboard, but I also want it to run normally when the
programming cable is unplugged. Do I leave the port A pins floating,
grounded, tied high ???
>
> I've read through the datasheet and the prototyping board schematic,
and the application notes but cant come up with a definative answer.
>
> If anyone can help, that would be great. Thanks.
> Jon.
>
------------------------------------
(You need to be a member of rabbit-semi -- send a blank email to rabbit-semi-subscribe@yahoogroups.com )
possible for them to float to a mid-range voltage and cause
unnecessary current draw. Best option is leave them as inputs and tie
them high/low, or else make them outputs.
That said, I've never had problems with floating inputs either :v)
-Lynn
--- In r...@yahoogroups.com, Shawn Upton
>
> I've had no problems letting unused pins float on my applications.
>
> Shawn Upton, KB1CKT
>
> ----- Original Message ----
> From: Jonathan Loechel
> To: r...@yahoogroups.com
> Sent: Thursday, October 2, 2008 9:12:28 PM
> Subject: [rabbit-semi] Motherboard PCB Design for RCM3000 Question
> Hi, Im designing a motherboard PCB for the RCM3000 to plug into as
part of a university poject.
>
> I just want to check that what I am doing is correct.
> I am planning to set the pins on the parallel ports that I am not
using (all of B, D, and E and half of F and half of G) as output pins
and then leave them floating on the PCB. Is this correct??
>
> Im also unsure of what to do with the Port A pins. I want to be able
to use the programming connector to reprogram the RCM3000 while it's
on the motherboard, but I also want it to run normally when the
programming cable is unplugged. Do I leave the port A pins floating,
grounded, tied high ???
>
> I've read through the datasheet and the prototyping board schematic,
and the application notes but cant come up with a definative answer.
>
> If anyone can help, that would be great. Thanks.
> Jon.
>
------------------------------------
(You need to be a member of rabbit-semi -- send a blank email to rabbit-semi-subscribe@yahoogroups.com )
Re: Motherboard PCB Design for RCM3000 Question - fairy_dave - Oct 7 17:00:58 2008
--- In r...@yahoogroups.com, "lwoodzw" wrote:
>
> It's best not to let unused pins sit around as floating inputs, it's
> possible for them to float to a mid-range voltage and cause
> unnecessary current draw. Best option is leave them as inputs and
tie
> them high/low, or else make them outputs.
>
> That said, I've never had problems with floating inputs either :v)
>
> -Lynn
I find as a general rule of thumb that on a board floating is fine but
on a chip it's nasty. Reason being most boards will have pull up/down
resistors or other forms of buffering so that the pin will have a
default state, whereas chips often leave this out as it can make design
harder to work with, makes the chip more expensive, etc. It's only a
rule of thumb of course but still a good guide I have found over the
years.
------------------------------------
(You need to be a member of rabbit-semi -- send a blank email to rabbit-semi-subscribe@yahoogroups.com )
>
> It's best not to let unused pins sit around as floating inputs, it's
> possible for them to float to a mid-range voltage and cause
> unnecessary current draw. Best option is leave them as inputs and
tie
> them high/low, or else make them outputs.
>
> That said, I've never had problems with floating inputs either :v)
>
> -Lynn
I find as a general rule of thumb that on a board floating is fine but
on a chip it's nasty. Reason being most boards will have pull up/down
resistors or other forms of buffering so that the pin will have a
default state, whereas chips often leave this out as it can make design
harder to work with, makes the chip more expensive, etc. It's only a
rule of thumb of course but still a good guide I have found over the
years.
------------------------------------
(You need to be a member of rabbit-semi -- send a blank email to rabbit-semi-subscribe@yahoogroups.com )