Download the dwl application with only rx and tx ua

Is this posible?
i want to load a dwl application into the quick 2406 but the modem it is build into a pcb board, and only get acces to rx and tx of uart1,

i have communication over the uart 1 i can execute any at command from there, but when i try to load a new program with at+wdwl the modem does not show me the $$$$$ strings in the hyperterminal waiting for a new file to load.

any ideas?

Hi ofernandez,
I think the wdwl fails because if you use only tx and rx, then the flow control pins are not available. The +WDWL might use the flow control signals to properly perform the download process. This is because, downloading is a critical process which will require flow control capabilities (so that wrong data is not written).
I am not sure, but this can be the cause of the problem.

Best Regards,
Open AT Fan.

I don’t know for sure, but I think the $$$ may be generated by Hyperterminal to show the user that it is ready to send a file… I am using Tera Term Pro, and this terminal program also does not show $$$ - so I think they might not be transmitted from the modem…

Best Regards,

Hi jan,
The $$$ symbols which are displayed in the hyperterminal when AT+WDWL command is given are nothing but the NACK control characters which are sent by the XModem or 1KXModem protocol to tell the sender to initiate the data transfer. In your case, were you able to download the file properly without receiving the $$$ symbols?
In case, you were able to download, it means that the NACK control characters were send but you were not able to see them because in some utilities, the control characters (like NACK) are not displayed but actually they are received.
In Hyperterminal too, if you change the FONT from “TERMINAL” (which is default) to COURIER, you will not see the $$$ symbols but will instead see the ||| symbols.

Even in TE, if you given AT+WDWL command, you will see that ||| symbols appear in the data window (though you will not be able to send the dwl file from there as TE, does not implement the XModem/1kXModem protocol which is required by the module to get the file from the sender).

Best Regards,
Open AT Fan.

the final idea is that is not posible to download if we do not have hardware control flow, from that ppoint we need the data ready signals too.

That shouldn’t be a problem - the XMODEM protocol should ensure that bad data is detected & rejected.

Also, the XMODEM protocol does not allow the next block to be sent until the previous one has been ACKed - so it effectively has its own built-in flow control…

But I don’t think software flow control can be used with XMODEM - because the XON/XOFF characters could be misinterpreted as data…

need hardware control flow that needs dataready signals, that is for sure,
Xon/Xoff are not chars are signals in diferents pins of serial port, to make some synch.

No, that is incorrect! :open_mouth:

XON and XOFF most certainly are characters!
In fact, they are the DC1 and DC3 characters - ASCII Hex codes 0x11 and 0x13


i do not know what your terminal does with the CTS and RTS signals these are the XON / XOFF flow control signals on a com port, and they are physical signals they are not in the RX and TX, you better take a look how rs232 works

[color=red]No, they are not! :open_mouth:

CTS and RTS are the hardware flow-control signals; they are physical signal connections between the DTE and DCE.
This is a type of out-of-band signalling

XON and XOFF are used in software flow control; they are control characters (DC1 and DC3, in fact) sent along the RxD and TxD lines like any other data.
This is a type of in-band signalling

You need to read that Wikipedia article:

yes you are rigth, the chars are send, as i read.

but let me tell you an history about windows hyperterminal an Q2406
i try XON/XOFF with only RX/TX-GND and it does not work.
i did a cable with cts and rts optional connection and XON/XOFF and it works

this is my experience here, if i need XON/XOFF i need the signals CTS/RTS, and say something more with that lines you can not update the firmware it need DTR signals too (real hardware control flow)

The module (probably) requires RTS to be asserted whether or not you use it for flow control.
You need to add a “loopback” from CTS to RTS - as shown here: … .php?t=419

Try the loopback - I think you’ll find it works! :slight_smile:

Add the DTR to DSR loopback also shown in … .php?t=419

Despite this, it does seem that the Wavecom download does require the use of hardware flow-control - especially when using 1K-XMODEM :cry:

So, this appears to be a fault in Wavecom’s XMODEM implementation? :cry:

Open AT Fan was right:

See also: … =6344#6344

Seems to have been fixed by R73a: … 212#p24212