Lpc2000

(Sorry if this email is coming multiple times, but it looks like i 
have problems sending email to the mailinglist...)

Hello,

first many thanks to philips_marketing_usa for posting a 
preliminary "LPC214x Preliminary Datasheet". I read around in it 
especially for the new USB feature, but have some additional 
questions (forgive me if they are easy questions, i am not too deep 
familiar with technical details of USB).

1) The LPC2148 supports USB 2.0 in full speed. Is this backward 
compatible to the 12 MBit/s when i have only an USB 1.1 host (e.g. 
my laptop) ?  

2) Can i use choose from different oscillators (e.g. my favorite 
14,745 MHz, because of the possible variety of UART baudrates, also 
high ones) or is it restricted e.g. to a 24 MHz oscillator if i want 
to use USB ?

3) Is there any suggested pcb layout for the USB lines of the 
LPC2148 from philips ? Ok, i think i must use the shortest lines for 
D+ and D-, but is there a need for ground planes, filters,... ? Just 
for a quick prototype, to get it up and running, is this also 
needed ? I think bits are going over D+ and D- with 480 MBit/s, even 
when only 12 MBit/s are used for LPC2148. Is this correct ?

4) What is "Soft Connect USB Feature" in detail ?

5) As earlier mentioned in a posting in the mailinglist, is it 
correct, that the two 33 Ohm resistors sit in line of D+ and Vbus 
and not in lines D+ and D- ? What is Vbus in generally used, just to 
detect the presence of power from host ? So in general every 
interrupt line can be used ? Or is there something special, e.g. to 
detect if voltage is enough ?

6) What is Philips delivering for USB of LPC2148 ? A library 
(compiled for different compilers like gcc, ...) ? Example code for 
a minimal / complete USB stack ? How much Flash / RAM will be 
needed ? Will there be any example code for ARM of a serial 
interface ? Any x86 code for host side (Windows / Linux) ? Will the 
offered parts be free of charge or cost something ? When will it be 
available ?

7) When will a detailed User Manual be available for the LPC2148 ?

Many thanks for answers on the above questions !

Regards,

        Martin

> 1) The LPC2148 supports USB 2.0 in full speed. Is this backward 
> compatible to the 12 MBit/s when i have only an USB 1.1 host (e.g. 
> my laptop) ?  

USB 2.0 low and full speed devices should work with 1.1 hosts and hubs. 
 
> 2) Can i use choose from different oscillators (e.g. my favorite 
> 14,745 MHz, because of the possible variety of UART baudrates, also 
> high ones) or is it restricted e.g. to a 24 MHz oscillator if i want 
> to use USB ?

As I see it USB part has seperate PLL and therefore 14,745 could be
used (or any other). What I'd like to see in LPC2000 series is
additional CCLK divider on all chips. Or 32kHz PLL.

> 3) Is there any suggested pcb layout for the USB lines of the 
> LPC2148 from philips ? Ok, i think i must use the shortest lines for 
> D+ and D-, but is there a need for ground planes, filters,... ? Just 
> for a quick prototype, to get it up and running, is this also 
> needed ? I think bits are going over D+ and D- with 480 MBit/s, even 
> when only 12 MBit/s are used for LPC2148. Is this correct ?

Keep D+ and D- together and equal in length. 


> 4) What is "Soft Connect USB Feature" in detail ?

That means that you can control USB connection with software. I don't
think this is the case here. External resistor and switch are
connected (to pull up D+ i.e.) to output pin of LPC214x while in
ISP1181 you don't need all that (I heard somewhere that ISP1181 is
inside of LPC214x). 

> 5) As earlier mentioned in a posting in the mailinglist, is it 
> correct, that the two 33 Ohm resistors sit in line of D+ and Vbus 
> and not in lines D+ and D- ? What is Vbus in generally used, just to 
> detect the presence of power from host ? So in general every 
> interrupt line can be used ? Or is there something special, e.g. to 
> detect if voltage is enough ?

Put two resistors in line of D+ and D-. As I can see in datasheet the
correct value is 18 Ohm. Total driver resistance is between 29 and 44
Ohm with note that this includes 18 Ohm external resistors on D+ and D-.
Vbus is used for detection and power supply (read the specification
for limitations). 

> 6) What is Philips delivering for USB of LPC2148 ? A library 
> (compiled for different compilers like gcc, ...) ? Example code for 
> a minimal / complete USB stack ? How much Flash / RAM will be 
> needed ? Will there be any example code for ARM of a serial 
> interface ? Any x86 code for host side (Windows / Linux) ? Will the 
> offered parts be free of charge or cost something ? When will it be 
> available ?

Nothing for now. :) Examples are available for standalone USB devices
and could be implemented with LPC214x with little effort (no user
LPC214x manual no USB).

> 7) When will a detailed User Manual be available for the LPC2148 ?

I hope very soon. 

BR,
Slawc

On Mon, Jul 11, 2005 at 09:26:09PM -0000, slawcus wrote:
>  
> > 1) The LPC2148 supports USB 2.0 in full speed. Is this backward 
> > compatible to the 12 MBit/s when i have only an USB 1.1 host (e.g. 
> > my laptop) ?  
> 
> USB 2.0 low and full speed devices should work with 1.1 hosts and hubs. 

USB 2.0 full speed is identical to USB 1.1 except for the version
number in the device descriptor, which you can choose to set to 1.1
anyway if you prefer.

> > needed ? I think bits are going over D+ and D- with 480 MBit/s, even 
> > when only 12 MBit/s are used for LPC2148. Is this correct ?

No, the translation from 480Mb/s is done in the hub - your device will
never see anything faster than 12 Mb/s.


-- 
Clyde Stubbs                     |            HI-TECH Software
Email: clyde@...          |          Phone            Fax
WWW:   http://www.htsoft.com/    | USA: (408) 490 2885  (408) 490 2885
PGP:   finger clyde@...   | AUS: +61 7 3552 7777 +61 7 3552 7778
---------------------------------------------------------------------------
HI-TECH C: compiling the real world.

> > 3) Is there any suggested pcb layout for the USB lines of the 
> > LPC2148 from philips ? Ok, i think i must use the shortest lines 
for 
> > D+ and D-, but is there a need for ground planes, filters,... ? 
Just 
> > for a quick prototype, to get it up and running, is this also 
> > needed ? I think bits are going over D+ and D- with 480 MBit/s, 
even 
> > when only 12 MBit/s are used for LPC2148. Is this correct ?
> 
> Keep D+ and D- together and equal in length. 

Per the USB Spec, these need to be matched differential pairs at 90 
ohms of impedance.  This can be very difficult to achieve on a two 
layer 0.062 PCB board.


> > 4) What is "Soft Connect USB Feature" in detail ?
> 
> That means that you can control USB connection with software. I 
don't
> think this is the case here. External resistor and switch are
> connected (to pull up D+ i.e.) to output pin of LPC214x while in
> ISP1181 you don't need all that (I heard somewhere that ISP1181 is
> inside of LPC214x). 

A Full Speed USB function device anounces it self to the USB 
controller, by pulling D+ hi with about a 1.5K ohm resister.  The 
Softconnet feature allow you to control when this happens...

> 
> > 5) As earlier mentioned in a posting in the mailinglist, is it 
> > correct, that the two 33 Ohm resistors sit in line of D+ and 
Vbus 
> > and not in lines D+ and D- ? What is Vbus in generally used, 
just to 
> > detect the presence of power from host ? So in general every 
> > interrupt line can be used ? Or is there something special, e.g. 
to 
> > detect if voltage is enough ?
> 
> Put two resistors in line of D+ and D-. As I can see in datasheet 
the
> correct value is 18 Ohm. Total driver resistance is between 29 and 
44
> Ohm with note that this includes 18 Ohm external resistors on D+ 
and D-.
> Vbus is used for detection and power supply (read the specification
> for limitations). 
> 

I guess I missed the section in the datasheet that showed 18ohms.  
The included ref circuit shows 33ohms on D+/D-.  On VBus it depends 
if you are using a self powered device vs. a Bus powered device.  On 
self powered, I usually add a 10k, and just use this in my own 
SoftConnect functionality.  I don't bring it to Vcc (5v) as I don't 
what my powersupply, and the pc's duking it out... so to speak.  On 
bus powered devices, this is where you can draw your power.  Again 
by spec, you cannot draw more than 100ma, until you have been given 
permission by the host controller.  The most that you can draw is 
500ma, if the host controller grants this...

If you are planning on doing USB, please get the spec and join 
USB.org.  There are a lot of resources over there.  (Plus you will 
need your own manufacturer's id.)

Tim Larson
Great Notions

Hello Slawc,

first many thanks for your answer !

> As I see it USB part has seperate PLL and therefore 14,745 could be
> used (or any other). What I'd like to see in LPC2000 series is
> additional CCLK divider on all chips. Or 32kHz PLL.

Ok, i found the separate PLL in the overview diagram on page 3 of the 
preliminary data sheet from 22 June 2005. But this doesn't mean that i reach 
a USB suitable frequency (i think something like 12 MHz) from my odd 
frequency 14,745 MHz, even if i have a separate PLL ?

> Put two resistors in line of D+ and D-. As I can see in datasheet the
> correct value is 18 Ohm.

Where (on which page) have you found the 18 Ohm resistors ?

> Total driver resistance is between 29 and 44
> Ohm with note that this includes 18 Ohm external resistors on D+ and D-.

Ok, the 29 to 44 Ohm are in table 10 page 31. But then also the 33 Ohm 
values could be correct, because total is 33 Ohm which is in this 
interval...

Regards,

        Martin

> Ok, i found the separate PLL in the overview diagram on page 3 of 
the 
> preliminary data sheet from 22 June 2005. But this doesn't mean 
that i reach 
> a USB suitable frequency (i think something like 12 MHz) from my 
odd 
> frequency 14,745 MHz, even if i have a separate PLL ?

48 is close to 13/4 * 14,745 (If PLL will work that way). Using only 
12MHz quartz is useless. 
 
> > Put two resistors in line of D+ and D-. As I can see in datasheet 
the
> > correct value is 18 Ohm.
> 
> Where (on which page) have you found the 18 Ohm resistors ?

LPC2148 datasheet, page 31 note 9. Replace W with omega (common 
mistake in documents). I think 18 Ohm value is correct value for 
external resistor (at least all other standallone USB devices from 
Philips have resistors with values around 20 Ohm). 

Philips apps ... knock knock ... :)