[lowrisc-dev] KC705 support

Armia Salib armiasalib at yahoo.com
Tue Aug 22 19:50:45 BST 2017


Thank you, Wei, Stefan and Dr Jonathan for this support. We will share with you our changes to support KC705 once it is done.

--------------------------------------------
On Tue, 8/22/17, Dr Jonathan Kimmitt <jrrk2 at cam.ac.uk> wrote:

 Subject: Re: [lowrisc-dev] KC705 support
 To: lowrisc-dev at lists.lowrisc.org
 Date: Tuesday, August 22, 2017, 11:29 AM
 
 The KC705 .xdc file mentions two
 signals
 
 set_property
 PACKAGE_PIN M19 [get_ports USB_TX]
 set_property IOSTANDARD LVCMOS25 [get_ports
 USB_TX]
 set_property PACKAGE_PIN K23
 [get_ports USB_RTS]
 set_property IOSTANDARD
 LVCMOS25 [get_ports USB_RTS]
 set_property
 PACKAGE_PIN K24 [get_ports USB_RX]
 set_property IOSTANDARD LVCMOS25 [get_ports
 USB_RX]
 set_property PACKAGE_PIN L27
 [get_ports USB_CTS]
 set_property IOSTANDARD
 LVCMOS25 [get_ports USB_CTS]
 
 You will note that the sense is the opposite of
 what a rational person 
 would do
 (i.e. it refers to the PC side). This may mean
 you need to reverse the 
 sense of
 CTS and RTS. Referring to the circuit diagram
 from the Xilinx website 
 might help here.
 
 Also the SD interface needs a
 reset. I have tentatively connected this to
 
 set_property PACKAGE_PIN Y21
 [get_ports sd_reset]
 set_property IOSTANDARD
 LVCMOS25 [get_ports sd_reset]
 
 but in the Xilinx .xdc file, this is identified
 as SDIO_SDWP
 
 The SD/MMC
 card specification history has a long history of changing
 
 names, so this also
 needs
 careful review.
 
 Getting
 these pins to actually work in hardware is another matter as
 
 Stefan points out.
 
 Jonathan
 
 On
 22/08/17 11:16, Stefan Wallentowitz wrote:
 > On 22.08.2017 12:04, Wei Song wrote:
 >> The 'rts' and 'cts'
 signals are used for UART hardware flow control
 >> which is used to support the high baud
 rate.
 >> Actually I am not the most
 knowledgable person on this matter.
 >>
 On our mail list, Jonathan and Stefan have already started
 to provide
 >> information regarding
 UART.
 >> Stefan is the original author
 for this high speed UART interface, which
 >> amazed me initially as well.
 > Hi Armia,
 >
 > the UART chip on the KC705 is a joke. As
 you correctly observed, it only
 >
 supports 1MBaud. But beyond that it doesn't have
 hardware flow control,
 > which the
 current implementation needs. Anyhow, for testing and
 ramping
 > up that should be okay, but for
 traces it may become an issue. There is
 >
 the plan to add XON/XOFF flow control this winter, that will
 be helpful
 > then.
 >
 > As I said the only
 setup we currently support is the Cypress Superspeed
 > (USB 3.0) FMC board. We use it on the
 VCU108 in another project but with
 > the
 same debug interface and it works like a charm. I also have
 a FT300
 > FMC board here, but again
 won't find time before October/November to get
 > it running.
 >
 > If anyone of you would like to work on it
 instead, I am happy to assist.
 >
 > Cheers,
 > Stefan
 >
 
 
 



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