USBDM with serial interface

MarkK — Sat, 10 Mar 2012 02:01:12 GMT

We would like to add the USBDM circuit to our existing S9S12P based design to allow in-circuit code updates for the S9S12 via a USB port. The S9S12P processor currently communicates with the outside world via an RS232 serial interface. We are also interested in changing from this existing RS232 serial interface to a USB interface for communciations to the outside world. Can the USBDM circuit with the serial interface handle both of these functions (S9S12P programmer and USB to serial bridge)? If so, is firmware available for the MC9S08JS16 chip to allow it to handle both of these functions? How would the 08 chip be instructed to change between these functions? Do you have any recomendations for PC software to communicate with the 08 chip when it is acting as a USB to serial bridge?

Thanks,

Mark

Re: USBDM with serial interface

pgo — Sat, 10 Mar 2012 19:20:19 GMT

Dear Mark,

There is a USBDM JS16 design described on this page:

http://usbdm.sourceforge.net/USBDM_V4.9/USBDM_JS16/html/index.html

The first design given includes the USB Serial interface. If you are connecting to a 9S12 device using the same 5V power supply then the buffers for level conversion on the serial lines may be omitted.

This is a composite device i.e. when plugged in it appears as two separate devices:

USBDM BDM Interface
CDC interface (serial port).

While it is possible to use both at the same time this will increase the number of characters dropped by the serial interface at higher speeds. Otherwise the two interfaces are pretty much independent and may be operated at the same time. There is no switching between functions,

Any of the many PC serial programs may be used with the serial port. The only issue is that the BDM may be assigned a COM port number that is quite high for example COM33:, though this can be altered in the device manager. With this proviso, I have found OCConsole a simple and convenient program. You can even use Hyperterminal but it's a program that I find annoying.

bye

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USBDM with serial interface

Re: USBDM with serial interface