Author Topic: Sending Break Detect RS232 Signal on P89LPC921 device  (Read 3312 times)

Guillaume

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Sending Break Detect RS232 Signal on P89LPC921 device
« on: October 07, 2005, 07:26:47 am »
Hello,

I would like to use the Break Detect Function in RS232 Serial port to enable the BOOT STATUS and enter in ISP Mode when Reset.
I have seen that I must to enable the EBRR Bit to enable this function. But the User Manual explain that the Break Detect occurs when a start bit, 8 data bits and 2 stop bit occurs (For Mode 1 that I use).
How can I send this Break Detect Signal with a Hyper terminal.
My objectif is to send a string (ISP_ON) that set the EBBR bit and active the EBRR function, and to send the "Break Detect" signal to activ the ISP_Mode.
Could you explain me more how to do that.

Thanks

Jan Waclawek

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Re: Sending Break Detect RS232 Signal on P89LPC921 device
« Reply #1 on: October 10, 2005, 01:39:45 am »
I hope it's clear for you how it works - your program has to set the EBRR bit; then upon reception of the break signal (i.e. a "zero" on the Rx pin for longer than one character time) the LPC9xx will automatically reset to the bootloader. If you are sure that break cannot occur spuriously, it is perhaps not a bad idea to enable it immediately after reset... (but if you are sure in what you are doing, do it your way).

Hyperterminal is quite a dumb terminal program and it's only advantage is that it is readily available on almost all computers with Win (so one does not need to carry it around e.g. at the customer). Try TeraTerm (Control->Send break (AltB); or try http://realterm.sf.net - the latter has good features for the RS232 lines' control, but the program itself has a little bit messy look... (and a bug when transmitting files, but that's not what you need now).

Jan Waclawek

Guillaume

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Re: Sending Break Detect RS232 Signal on P89LPC921 device
« Reply #2 on: October 10, 2005, 05:09:21 am »
I have tried TeraTerm Pro v3.1.3 (downloaded on http://www.ayera.com/teraterm/) and the "Send Break" command works very good.

Thanks a lot

Rem. : The device is in ISP mode as long as the power is present.
When a new POR occurs, the device boot at the reset segment and run the application (Boot Status=0). This is not clearly written in the P89LPC921 User Manual.