Hi Group,

how fast can I run the UART on a MSP430? 230,4 kbit/s? ...?

cm

Hi,

> how fast can I run the UART on a MSP430? 230,4
kbit/s? ...?

In SPI mode and with a 8 MHz quartz you can run it with up to 4 Mbit/s. I'm
using this speed for communication with MMC and SD Cards.
With overclocking you can get 10 Mbit/s.

Rolf F.

Rolf,

What is the overclocking crystal freq, what is the current 
consumption, any idea? - just curious.
Graham.

--- In msp430@msp4..., <nobodyo@w...> wrote:
> Hi,
> 
> > how fast can I run the UART on a MSP430? 230,4 kbit/s? ...?
> 
> In SPI mode and with a 8 MHz quartz you can run it with up to 4 
Mbit/s. I'm using this speed for communication with MMC and SD
Cards.
> With overclocking you can get 10 Mbit/s.
> 
> Rolf F.
> 
> 
> 

Rolf,

and in UART mode? I did not find any information about the maximum UART 
speed on the TI page (in UART mode!).

cm

nobodyo@nobo... wrote:
> Hi,
> 
> 
>>how fast can I run the UART on a MSP430? 230,4 kbit/s? ...?
> 
> 
> In SPI mode and with a 8 MHz quartz you can run it with up to 4 Mbit/s.
I'm using this speed for communication with MMC and SD Cards.
> With overclocking you can get 10 Mbit/s.
> 
> Rolf F.
> 
> 
> 
> 
> 
> 
> .
> 
>  
> 
> ">http://docs.yahoo.com/info/terms/ 
> 
> 
> 

I have successfully used MSP430F123 at 460.8kbps
I used very short wires (3-4 inches) from the micro to
a RS232 level converter (Maxim chip). Then used RS232
to USB adapter to capture data in hyperterminal.

-Sumukh

--- cm <cm.groups@cm.g...> wrote:
> Rolf,
> 
> and in UART mode? I did not find any information
> about the maximum UART 
> speed on the TI page (in UART mode!).
> 
> cm
> 
> nobodyo@nobo... wrote:
> > Hi,
> > 
> > 
> >>how fast can I run the UART on a MSP430? 230,4
> kbit/s? ...?
> > 
> > 
> > In SPI mode and with a 8 MHz quartz you can run it
> with up to 4 Mbit/s. I'm using this speed for
> communication with MMC and SD Cards.
> > With overclocking you can get 10 Mbit/s.
> > 
> > Rolf F.
> > 
> > 
> > [Non-text portions of this message have been
> removed]
> > 
> > 
> > 
> > .
> > 
> >  
> > 
> > ">http://docs.yahoo.com/info/terms/ 
> > 
> > 
> > 
> 
> 
> 
> 


__________________________________

Hi,

> and in UART mode? I did not find any information
about the maximum UART
> speed on the TI page (in UART mode!).

i don't know.
You should ask TI ( epic@epic... ).

Regards

Rolf F.

2,457,600 baud @ 7.3728MHz crystal on XT2 (or 2,666,667 baud @ 8.0000MHz) 
is the maximum rate at which the hardware will work. This is faster than an 
interrupt can process the data, of course, since a 10-bit asynchronous 
frame at 2,457,600 baud takes only 4 uSecs per byte and interrupt latency 
is 6uSecs overhead plus instructions. Also you'd generally need to be 
looking at RS485 physical layer drivers rather than RS232 when you go much 
above 250 kBaud, unless you connect without interface drivers.

Where does this maximum figure come from? The maximum USART baud rate is 
one-third the UART source clock frequency BRCLK, regardless of clock 
source. The reason for this is the 3-way majority voting used in the 
receiver. ie you can't set U0BR1,0 to 0.

According to the User Manual: "Timing for each bit is shown in Figure 138.

For each bit received, a majority vote is taken to determine the bit value. 
These samples occur at the N/21, N/2, and N/2+1 BRCLK periods, where N is 
the number of BRCLKs per BITCLK."

Thus the minimum allowed values for the baud rate divisor is 0x0003:

UBR01 = 0x03; // 7.3728MHz /3 => 2,457,600 baud
UBR11 = 0x00; //

UBR01 = 0x03; // 8.0000MHz /3 => 2,666,667 baud
UBR11 = 0x00; //

Hope this helps.
Hugh

At 15:20 18/06/2003 +0200, you wrote:
 > Rolf,

 > and in UART mode? I did not find any information about the maximum UART
speed on the TI page (in UART mode!).

cm

nobodyo@nobo... wrote:
 > Hi,
 >
 >
 >>how fast can I run the UART on a MSP430? 230,4 kbit/s? ...?
 >
 >
 > In SPI mode and with a 8 MHz quartz you can run it with up to 4 Mbit/s. 
I'm using this speed for communication with MMC and SD Cards.
 > With overclocking you can get 10 Mbit/s.
 >
 > Rolf F.

Hi,

> What is the overclocking crystal freq, what is the
current
> consumption, any idea? - just curious.
> Graham.

Others here have reported that they are using quartzes with up to 20 MHz.
The current consumption is in good approximation const.*frequency.

Rolf F.

Hi,

> Where does this maximum figure come from? The
maximum USART baud rate is
> one-third the UART source clock frequency BRCLK, regardless of clock
> source. The reason for this is the 3-way majority voting used in the
> receiver. ie you can't set U0BR1,0 to 0.

in SPI mode the smallest division factor is two, so the limit (without
overclocking) is 4 Mbit/s.

Rolf F.

Hi Rolf,

As soon as I hit the send button I thought to myself - dumb question. 
If SPI 4mbit/s = 8mhz xtal, then 10mbit/s must be 20mh/z

> I'm using this speed for communication with
MMC and SD Cards.
> With overclocking you can get 10 Mbit/s.
> 
> Rolf F.

I am interested in your comment about MMC + SD cards though. Sometime 
in the near future we will be wanting to datalog and these cards 
would be ideal. Is it easy to buy the sockets for them, and is the 
software easy? - Perhaps there are examples out there somewhere?

GrahamG.