On 05/09/2018 08:54, smf wrote: > > "On-chip baud rate generator: 15 programmable baud rates from a > standard 1.8432 Mhz external crystal (50 to 19,200 baud)." > > "External 16x clock input for non-standard baud rates (up to 125Kbaud)" > I forgot to mention, later in the datasheet it's clear that a crystal and clock are different things. "XTAL1, XTAL2 (Crystal Pins) These pins are normally directly connected to the external crystal (1.8432 MHz) used to derive the various baud rates. Alternatively, an externally generated clock may be used to drive the XTAL1 pin, in which case the XTAL2 pin must float. XTAL1 is the input pin for the transmit clock." The block diagram shows that the /16 is always active, the baud rate generator takes XTAL1 & XTAL2 and bits 0-4 of the control register. I don't know what happens electrically when you switch the internal baud rate generator off, which the datasheet indicates the XTAL2 must float and it's not floating because it's hooked up to a crystal. It certainly doesn't make it at all clear that it's supported. It's also not clear how bidirectional the RxC pin is either, when using the on baud generator the block diagram just shows that it gets hooked up internally to the RxC pin. So if you had something supplying an RxC input as well then it's not clear that the external clock would be ignored.Received on 2018-09-05 11:00:04
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