Raw Synchronous Serial

I need to send and receive synchronous serial data in raw mode. There is no 0x7e header and there is no termination frame or bits. Merely a continuous stream of serial data and a clock with a sync pattern every 270 “words” with a word being 12 bits.

It appears Serial Ports E&F are hardware constrained to only handle asyn or HDLC? I thought this was based on the older Zilog serial processors which indeed did support raw serial modes.

I am using a RCM4310 and I want to avoid using ports A&B due to clock sharing and the programming port with other devices. I need C&D as well and the CLK lines are doubled up with E&F so it is really difficult to change paths.

My processor is preceded with a FPGA so I suppose I could do a sync serial to async converter or sync to HDLC but what a pain.

Surely this processor can support raw serial mode?

See TN213 Rabbit Serial Port Software at this link http://www.digi.com/support/productdetail?pid=4978&type=documentation

We have RS232.lib which is the stream-based driver and packet.lib which is the frame-based driver.

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Except these are asynchronous protocols?

For complete details on the serial ports see the Rabbit 4000 processor user manual.

Synchronous is HDLC.

No, synchronous is not HDLC. HDLC is a serial synchronous protocol but so is SPI for example. HDLC packets are framed with a 0x7e before and after the packet and include a 16 bit CRC.


I have seen many HDLC controllers that support Raw mode in which the data is not framed nor requires the start stop flags.

Back to the drawing board.