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From: trungnl on 29 Nov 2005 09:19
>trungnl wrote:
>> Has anybody worked with PL2303 ? Please give me some help !
>
>When I wrote a driver for this chip, I gleaned the apparently
>reverse-engineered interface information from the appropriate
>Linux device driver.
>


>When I wrote a driver for this chip, I gleaned the apparently
>reverse-engineered interface information from the appropriate
>Linux device driver.
>

Hi Michael,

Actually I am writting the PL2303 driver base on some reverse-engineered
information retrieved by monitoring the data transfer process between a
PL2303-based USB-RS232 cable and PC. Now I can enumerate the PL2303, set
the COM settings like baudrate, stop bits, parity... I can send as many
data as I like from the embedded USB host to PL2303 as well. But there is
still a big problem because the host cannot get data from PL2303.
Now I need some more information on:
1. How to be notified when there's some data in the Receive buffer of
PL2303.
2. How to know the amount of data in the Receive buffer of PL2303.

Best,
N.L.Trung

From: Meindert Sprang on 29 Nov 2005 09:46
"trungnl" <ngolamtrung(a)yahoo.com> wrote in message
news:xsadnTWnQpEQ_hHeRVn-ug(a)giganews.com...
> Actually I am writting the PL2303 driver base on some reverse-engineered
> information retrieved by monitoring the data transfer process between a
> PL2303-based USB-RS232 cable and PC. Now I can enumerate the PL2303, set
> the COM settings like baudrate, stop bits, parity... I can send as many
> data as I like from the embedded USB host to PL2303 as well. But there is
> still a big problem because the host cannot get data from PL2303.
> Now I need some more information on:
> 1. How to be notified when there's some data in the Receive buffer of
> PL2303.

You have to poll the PL2303 for that. Remember, USB is a master/slave system
where a slave NEVER starts transmitting by itself. Transmission of a slave
is always a response to a request from the master.

Meindert


From: Arie de Muynck on 29 Nov 2005 14:47
"trungnl" ...
>
> I am writting a firmware to connect an embedded USB host with the Prolific
> PL2303 USB-RS232 chip. The PL2303 chip is used to get data from some
> RS232-enabled devices and then transfer these data to the USB host. Now I
> need detailed information about PL2303's specification and operation, to
> develope the appropriate driver for it.
> I have been searching for some PL2303 driver or programming guides but
> haven't found any of them yet.
>
> Has anybody worked with PL2303 ? Please give me some help !


You did read the datasheet and manuals at this site?

http://www.prolific.com.tw/eng/Download-2.asp?ID=17

Arie de Muynck



From: trungnl on 29 Nov 2005 23:24

>You did read the datasheet and manuals at this site?
>

Yes I did read all the docs at Prolific Website, but they lack all the
information needed to develop PL2303's driver. I think FTDI has a better
product, the FT232BM, but PL2303 is much cheaper so I must choose
Prolific's product to reduce overall cost.
From: trungnl on 29 Nov 2005 23:37

>You have to poll the PL2303 for that.

Thanks Meindert,

I have implemented a polling mechanism to get data from PL2303 to the
embedded host. But there is another problem

According to PL2303's spec, the chip has an 256-byte-buffer for each Tx
and Rx operation. But when I transfer a large amount of data (about 3KB)
to the RS232 interface of PL2303, the USB host can only read a few bytes
from the USB interface. It seems that the data in PL2303's buffer has lost
so I cannot read all the data transfered to RS232 interface.




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