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[ts-7000] Re: RS485 HD on TS7390

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Subject: [ts-7000] Re: RS485 HD on TS7390
From: "briandgallaway" <>
Date: Mon, 17 Sep 2012 17:16:52 -0000
--- In  Petr ©tetiar <> wrote:
>
> briandgallaway <> [2012-09-13 18:00:02]:
>
> > So now it looks like I'll need to write to the registers using mmap.
> > However, I do not know which address to write to for the TS7390.  I've seen
> > posts doing similar for the TS7260 and TS7800, but nothing for the TS73xx
> > series.
>
> From the docs:
>
>       Appendix C: TS-7390 FGPA Register Map
>
>       By default the Lattice FPGA on the TS-7390 is loaded with a system 
> controller
>       core at base physical address 0x600F_F080. Add that base to the offsets 
> below
>       to access these registers. These registers are all 16 bits wide and 
> should
>       therefore be accessed with 16 bit writes.
>
>          base + 0x06:
>             bit 06: 485 Full Duplex Control
>
> So just modify that many mmap bit fiddling examples you can find around and
> you're probably done.
>
> -- ynezz

I did see that, however there should be more than one bit for RS 485.  For the 
TS7260, this is the relevant documentation:

Value    MSB     MID     LSB     Mode
0x00     0       0       0       RS-232
0x01     0       0       1       Full-Duplex RS-485
0x02     0       1       0       -- Reserved
0x03     0       1       1       -- Reserved
0x04     1       0       0       Half-Duplex 9600 Baud
0x05     1       0       1       Half-Duplex 19.2Kbaud
0x06     1       1       0       Half-Duplex 57.6Kbaud
0x07     1       1       1       Half-Duplex 115.2Kbaud

COM2 will default to RS-232 mode at reset (COM2 mode register = Hex 00). In 
order to switch COM2 into Full duplex RS-485 mode, the COM2 Mode register at 
0x22C0_0000 must be set to Hex 01. In this mode, the TX drivers are always 
asserted.

In order to switch COM2 into half-duplex RS-485, then the COM2 mode register at 
0x22C0_0000 must be set to Hex 04, 05, 06 or 07 depending upon the baud rate 
required. A second COM2 Mode register at 0x2300_0000 must be set to Hex 01 if 
the COM2 is in half-duplex mode and the data format is using 8 data bits with 
parity or 8 data bits with 2 stop bits.

the above is from 
http://wiki.embeddedarm.com/w/index.php?title=TS-7260#Optional_RS-485_Support

Brian.



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