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 ;
What MAXIM chip is used on Spartan 3E 1600E Microblaze Board for RS232 communication?
Started by ●February 2, 2010
Reply by ●February 2, 20102010-02-02
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
Reply by ●February 2, 20102010-02-02
On 2 =D1=84=D0=B5=D0=B2, 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. > > -- glenI 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 RXD pin protects against accidental logic conflicts. I am really puzzled!
Reply by ●February 2, 20102010-02-02
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.
Reply by ●February 2, 20102010-02-02
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
Reply by ●February 2, 20102010-02-02
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
Reply by ●February 2, 20102010-02-02
>On 2 =D1=84=D0=B5=D0=B2, 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 boardhas>> > 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 RXDpin>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
Reply by ●February 2, 20102010-02-02
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.
Reply by ●February 2, 20102010-02-02
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
Reply by ●February 2, 20102010-02-02
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
