On Wed, Mar 27, 2013 at 7:39 PM, He Dajiang (I2R) <[email protected]>wrote:

> Hi Andris,
>
> Thx for your reply. I will give it a try.
> However, even 50KHz won't result in so much delay. Under 50KHz, it takes
> 20 microsecond (us) to tx one byte, isn't it?


Nope.  It take 20 uS to move one bit.




> For simple read or write operation, data plus protocol overhead (START,
> STOP, and ACK), total bytes transmitted may be just around 10, the delay
> should be less than 1 millisecond (ms). Is it due to the tinyos task
> scheduling? Well, I am just guessing.
> If it has sth to do with task scheduling, I want to try another way: is it
> possible to use native I2C c driver in stead of tinios module just like
> using wdt_enable(1) to do system reset? I guess the driver is already
> somewhere. Can you tell me how to use?
>
> Thx & Best Regards
> dajiang
>
> ________________________________________
> From: András Bíró [[email protected]]
> Sent: Thursday, 28 March, 2013 4:52:49 AM
> To: He Dajiang (I2R)
> Cc: [email protected]
> Subject: Re: [Tinyos-help] tinyos efficiency
>
> Hi,
>
> TinyOS uses 50kHz I2C, but you can use 100kHz i2c on most devices and
> 400kHz on some. Unfortunatly, there's no nice way to change the bitrate,
> you must change it in /tos/chips/atm128/HplAtm128I2CBusP.nc (TWBR register)
>
> Andris
>
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-- 
Eric B. Decker
Senior (over 50 :-) Researcher
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