[lowrisc-dev] lowrisc v0.5 - need help to change sd card from 3.3V to 1.8V

Anup Kini anupkini at gmail.com
Wed Feb 7 07:39:16 GMT 2018


Hi Jonathan,

I will compare with the nexys4 board and talk to the proFPGA team to check
if I need to make any changes.
Thank You.

Thanks & Regards,
Anup Kini.

On Wed, Feb 7, 2018 at 12:57 PM, Dr Jonathan Kimmitt <jrrk2 at cam.ac.uk>
wrote:

> In the nexys4ddr, the SD-card voltage control is implemented in external
> circuitry. It is an on/off controller. If you want to implement 1.8V, you
> still need to apply 3.3V at first, then follow the appropriate flow diagram
> in the SD card specification having enquired that the card supports this
> mode. It would be inappropriate to try to do this in the boot loader unless
> you plan to expand the block ram capacity quite a bit.
>
> Sent from my iPhone
>
> > On 7 Feb 2018, at 06:59, Anup Kini <anupkini at gmail.com> wrote:
> >
> > Hi All,
> >
> > I am currently running the bare-metal selftest example.
> >
> > I get the following response:
> > selftest> D
> > sdhci_minion_hw_reset();
> > sdhci_minion_hw_reset();
> > *Power = 3.3V*
> > Card clock disabled
> > Trying clock div = 255
> > Actual clock divider = 255
> > Card clock disabled
> > Trying clock div = 255
> > Actual clock divider = 255
> > Card clock enabled
> > cmd timeout
> > ...
> > sd_cmd_response[38:7]:00000000
> > sd_cmd_response[70:39]:00000000
> > sd_cmd_response[102:71]:00000000
> > sd_cmd_response[133:103]:00000000
> > sd_cmd_wait:00000000
> > sd_status:00000200
> > sd_cmd_packet[31:0]:00000000
> > sd_cmd_packet[47:32]:00000000
> > sd_data_wait:00000000
> > sd_transf_cnt:00000000
> > sd_detect:00000000
> > sd_xfr_addr:00000000
> > sd_align:00000000
> > clock_divider_sd_clk:00000000
> > sd_cmd_arg:00000000
> > sd_cmd_i:00000000
> > {sd_data_start,sd_cmd_setting[2:0]}:00000000
> > sd_cmd_start:00000000
> > {sd_reset,sd_clk_rst,sd_data_rst,sd_cmd_rst}:00000000
> > sd_blkcnt:00000000
> > sd_blksize:00000000
> > sd_cmd_timeout:00000000
> > cmd timeout
> >
> > ... the above set is repeated infinitely.
> >
> > In the current configuration, SD Card interface is running at 1.8V
> > (LVCMOS18).
> > When can update this change ?
> >
> > I did go through the minion_helper.c -> sdhci_write() function.
> > The second parameter, val carries different values, but I am unable to
> > figure out the main header to update this change.
> >
> >
> >
> > Thanks & Regards,
> > Anup Kini.
>
>


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