What MAXIM chip is used on Spartan 3E 1600E Microblaze Board forRS232 communication?

Hello All,

I have started using Xilinx Spartan3E 1600E Microblaze Development
Board and want to use its RS232 facility in my project. This board has
two RS232 connectors but I cannot figure out what UART it uses. I was
searching for UART chip on the board (I was actually searching for a
MAXIM chip) and have seen none.
The Xilinx board's manual (ug257) does not say what particular UART is
present on the board and just mention some MAXIM chip but where it is
on board?

The manual (ug257) also specifies connection between particular FPGA
and RS232 pins on this board:
for DTE

NET "RS232_DTE_RXD" LOC = "U8" | IOSTANDARD = LVTTL ;
NET "RS232_DTE_TXD" LOC = "M13" | IOSTANDARD = LVTTL | DRIVE = 8 |
SLEW = SLOW ;

and for DCE

NET "RS232_DCE_RXD" LOC = "R7" | IOSTANDARD = LVTTL ;
NET "RS232_DCE_TXD" LOC = "M14" | IOSTANDARD = LVTTL | DRIVE = 8 |
SLEW = SLOW ;

Alex <victous@gmail.com> wrote:

> I have started using Xilinx Spartan3E 1600E Microblaze Development
> Board and want to use its RS232 facility in my project. This board has
> two RS232 connectors but I cannot figure out what UART it uses. I was
> searching for UART chip on the board (I was actually searching for a
> MAXIM chip) and have seen none.

It would be unusual to put a UART on an FPGA development board.

You should implement one in the FPGA logic.

For ethernet, they put the PHY on board, as that is hard to do
in the FPGA (too much analog and/or fast circuitry), but the MAC
is normally done inside the FPGA.

The RS232 level shift/buffers should be on the board, though.

-- glen

On 2 фев, 09:14, glen herrmannsfeldt <g...@ugcs.caltech.edu>wrote:
> Alex <vict...@gmail.com> wrote:
> > I have started using Xilinx Spartan3E 1600E Microblaze Development
> > Board and want to use its RS232 facility in my project. This board has
> > two RS232 connectors but I cannot figure out what UART it uses. I was
> > searching for UART chip on the board (I was actually searching for a
> > MAXIM chip) and have seen none.
>
> It would be unusual to put a UART on an FPGA development board.
>
> You should implement one in the FPGA logic.
>
> -- glen

I also had this thought until had noticed that MAXIM UART device is
mentioned on page 61 of ug257:

The FPGA supplies serial output data using LVTTL or LVCMOS levels to
the Maxim device,
which in turn, converts the logic value to the appropriate RS-232
voltage level. Likewise,
the Maxim device converts the RS-232 serial input data to LVTTL levels
for the FPGA. A
series resistor between the Maxim output pin and the FPGA’s RXD pin
protects against
accidental logic conflicts.

I am really puzzled!

In comp.arch.fpga,
Alex <victous@gmail.com> wrote:
> On 2 фев, 09:14, glen herrmannsfeldt <g...@ugcs.caltech.edu> wrote:
>> Alex <vict...@gmail.com> wrote:
>> > I have started using Xilinx Spartan3E 1600E Microblaze Development
>> > Board and want to use its RS232 facility in my project. This board has
>> > two RS232 connectors but I cannot figure out what UART it uses. I was
>> > searching for UART chip on the board (I was actually searching for a
>> > MAXIM chip) and have seen none.
>>
>> It would be unusual to put a UART on an FPGA development board.
>>
>> You should implement one in the FPGA logic.
>>
>> -- glen
>
> I also had this thought until had noticed that MAXIM UART device is
> mentioned on page 61 of ug257:
>
> The FPGA supplies serial output data using LVTTL or LVCMOS levels to
> the Maxim device,
> which in turn, converts the logic value to the appropriate RS-232
> voltage level. Likewise,
> the Maxim device converts the RS-232 serial input data to LVTTL levels
> for the FPGA. A
> series resistor between the Maxim output pin and the FPGA’s RXD pin
> protects against
> accidental logic conflicts.
>
> I am really puzzled!

That's because you snipped the last line of Glen's reply:

>> The RS232 level shift/buffers should be on the board, though.

The 'Maxim' chip _is_ the level shifter. Should be something like a
MAX232 (google for that). But it will probably be a low voltage version
like the MAX3221 or a simular chip from another manufacturer.

So the UART is in the FPGA, the level shifter ("Maxim") outside. Isn't
there a schematic in the user guide?


--
Stef (remove caps, dashes and .invalid from e-mail address to reply by mail)

The soul would have no rainbow had the eyes no tears.

Alex <victous@gmail.com> wrote:
> On 2 ???, 09:14, glen herrmannsfeldt <g...@ugcs.caltech.edu> wrote:
>> Alex <vict...@gmail.com> wrote:
>> > I have started using Xilinx Spartan3E 1600E Microblaze Development
>> > Board and want to use its RS232 facility in my project. This board has
>> > two RS232 connectors but I cannot figure out what UART it uses. I was
>> > searching for UART chip on the board (I was actually searching for a
>> > MAXIM chip) and have seen none.

>> It would be unusual to put a UART on an FPGA development board.

>> You should implement one in the FPGA logic.

> I also had this thought until had noticed that MAXIM UART device is
> mentioned on page 61 of ug257:

It is just a level converter. The MAXIM MAX3232 device is popular
as it needs only +3.3V power, not the +/-12V used by most RS232
level converters. The MAX232 I used to know uses +5V, it
seems that there is now a 3.3V version. The capacitors are
used to generate the required voltages.

-- glen

Stef <stef33d@yahooi-n-v-a-l-i-d.com.invalid> wrote:
> In comp.arch.fpga,
> Alex <victous@gmail.com> wrote:

>>> > I have started using Xilinx Spartan3E 1600E Microblaze Development
>>> > Board and want to use its RS232 facility in my project. This board has
>>> > two RS232 connectors but I cannot figure out what UART it uses. I was
>>> > searching for UART chip on the board (I was actually searching for a
>>> > MAXIM chip) and have seen none.
(snip)

>> The FPGA supplies serial output data using LVTTL or LVCMOS
>> levels to the Maxim device, which in turn, converts the
>> logic value to the appropriate RS-232 voltage level. Likewise,
>> the Maxim device converts the RS-232 serial input data to LVTTL
>> levels for the FPGA.
(snip)

> That's because you snipped the last line of Glen's reply:

>>> The RS232 level shift/buffers should be on the board, though.

> The 'Maxim' chip _is_ the level shifter. Should be something like a
> MAX232 (google for that). But it will probably be a low voltage version
> like the MAX3221 or a simular chip from another manufacturer.

I believe it is the same board as the Spartan3E board, but with
a larger, pin compatible, FPGA.

> So the UART is in the FPGA, the level shifter ("Maxim") outside. Isn't
> there a schematic in the user guide?

See UG230.pdf I believe the MAX3232.

He has the microblaze manual, but that doesn't say much about
the rest of the board.

-- glen

>On 2 =D1=84=D0=B5=D0=B2, 09:14, glen herrmannsfeld
<g...@ugcs.caltech.edu>=
> wrote:
>> Alex <vict...@gmail.com> wrote:
>> > I have started using Xilinx Spartan3E 1600E Microblaze Development
>> > Board and want to use its RS232 facility in my project. This boar
has
>> > two RS232 connectors but I cannot figure out what UART it uses. I was
>> > searching for UART chip on the board (I was actually searching for a
>> > MAXIM chip) and have seen none.
>>
>> It would be unusual to put a UART on an FPGA development board.
>>
>> You should implement one in the FPGA logic.
>>
>> -- glen
>
>I also had this thought until had noticed that MAXIM UART device is
>mentioned on page 61 of ug257:
>
>The FPGA supplies serial output data using LVTTL or LVCMOS levels to
>the Maxim device,
>which in turn, converts the logic value to the appropriate RS-232
>voltage level. Likewise,
>the Maxim device converts the RS-232 serial input data to LVTTL levels
>for the FPGA. A
>series resistor between the Maxim output pin and the FPGA=E2=80=99s RX
pin
>protects against
>accidental logic conflicts.
>
>I am really puzzled!
>
>

A logic-level <-> RS232 converter is not a UART. It is a PHY.

As other posters have said, you put the UART (roughly equivalent to a MAC
into the FPGA, using a process known as "digital design".

If you only need one line speed, drop the 'U', and design an 'ART'.

HTH!


---------------------------------------
Posted through http://www.FPGARelated.com

Alex <victous@gmail.com> writes:

> The FPGA supplies serial output data using LVTTL or LVCMOS levels to
> the Maxim device, which in turn, converts the logic value to the
> appropriate RS-232 voltage level. Likewise, the Maxim device
> converts the RS-232 serial input data to LVTTL levels for the FPGA.
> A series resistor between the Maxim output pin and the FPGA¢s RXD
> pin protects against accidental logic conflicts.

> I am really puzzled!

Why? What you quoted does not mention a UART, what they describe is a
bog standard level shifter. I'm not sure if my board is the same as
yours, I have a "Spartan 3E 1600 Board" from Digilent, but I think
it's the same. The schematic for it shows a MAX3232 connected to the
serial ports, which is exactly that, a level shifter. Not a UART.

On Mon, 1 Feb 2010 23:01:47 -0800 (PST), Alex <victous@gmail.com>
wrote:

|Hello All,
|
|I have started using Xilinx Spartan3E 1600E Microblaze Development
|Board and want to use its RS232 facility in my project. This board has
|two RS232 connectors but I cannot figure out what UART it uses. I was
|searching for UART chip on the board (I was actually searching for a
|MAXIM chip) and have seen none.
|The Xilinx board's manual (ug257) does not say what particular UART is
|present on the board and just mention some MAXIM chip but where it is
|on board?
|
|The manual (ug257) also specifies connection between particular FPGA
|and RS232 pins on this board:
|for DTE
|
|NET "RS232_DTE_RXD" LOC = "U8" | IOSTANDARD = LVTTL ;
|NET "RS232_DTE_TXD" LOC = "M13" | IOSTANDARD = LVTTL | DRIVE = 8 |
|SLEW = SLOW ;
|
|and for DCE
|
|NET "RS232_DCE_RXD" LOC = "R7" | IOSTANDARD = LVTTL ;
|NET "RS232_DCE_TXD" LOC = "M14" | IOSTANDARD = LVTTL | DRIVE = 8 |
|SLEW = SLOW ;
|
|-----------------

The board is made by Digilent Inc for Xilinx and is sold on Digilent's
web page also.

The Max part is MaX3232 per the schematic.

james

Alex <victous@gmail.com> wrote:

> I have started using Xilinx Spartan3E 1600E Microblaze Development
> Board and want to use its RS232 facility in my project. This board has
> two RS232 connectors but I cannot figure out what UART it uses. I was
> searching for UART chip on the board (I was actually searching for a
> MAXIM chip) and have seen none.

The data sheet for the MAXIM MAX3232, MAX3222-MAX3241.PDF
gives much detail including a picture of the die of the MAX3222.
I believe it includes some fairly large (for modern digital IC)
transistors. The total transistor count is 339. Download
from maxim-ic.com

-- glen

james <bubba@bud.u> writes:

> The board is made by Digilent Inc for Xilinx and is sold on Digilent's
> web page also.
>
> The Max part is MaX3232 per the schematic.

Interestingly, now that I looked, mine actually has an ST3232 But
undoubtedly functionality is the same as MAX3232.

"Anssi Saari" <as@sci.fi> schrieb im Newsbeitrag
news:vg3zl3rw5xq.fsf@pepper.modeemi.cs.tut.fi...
> james <bubba@bud.u> writes:
>
>> The board is made by Digilent Inc for Xilinx and is sold on Digilent's
>> web page also.
>>
>> The Max part is MaX3232 per the schematic.
>
> Interestingly, now that I looked, mine actually has an ST3232 But
> undoubtedly functionality is the same as MAX3232.

Not exactly, the original MAX3232 is capable of transferring up to 1Mbaud,
the ST3232 400kbaud only.

MIKE

M.Randelzhofer <techseller@gmx.de> wrote:
(snip)

> Not exactly, the original MAX3232 is capable of transferring
> up to 1Mbaud, the ST3232 400kbaud only.

According to the Maxim data sheet only the MAX3237 can do
megabaud, and only when the MBAUD input is active. Otherwise
it is 250kbps.

The MAX3232 seems to specify the maximum data rate as
MIN 120kbps TYP 235kbps, load of 3k ohms, 1000pF, one transmitter
switching.

-- glen