Martin Belohorka

Can I use the AN2295 bootloader running at 115200 with the internal RC oscillator?

Discussion created by Martin Belohorka on Feb 2, 2010
Latest reply on Feb 4, 2010 by Pavel Lajsner



In order to save the cost of a crystal, I would like to be able to run the AN2295 bootloader in with the interanal RC oscilator calibrated t0 36 khz and, if possible, communication at a bitrate of 115200.


My PCB features a QE128 and a 4Mhz crystal.

Currently, the internal RC oscillator is calibrated to 32.768 kHz and the bootloader runs at a fast enough 38400. However, the usercode needs 115200, and therefore, the user code use the 4Mhz crystal instead, since 32.768 can't be used to generate 115200.


However, If I calibrate the internal RC- oscillator to 36 kHz, I can set the usercode generate 115200 from it (done through PE). If I do that however, the bootloader will not  generate its 38400.


In essence, I have no need a bitrate of 115200 in the bootloader. I do however need it to operate correctly with a 36khz (or other frequency that can be used for 115200 in user code) internal oscillator speed.


Have I made myself clear enough?

Can this be done at all?


Best regards