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Document the recently added get-bitmode and eeprom read/write functionality.

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This commit is contained in:
Ian Lepore 2015-08-06 20:59:03 +00:00
parent 1e2ec671fc
commit 374b1ec1ea
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=286389
1 changed files with 61 additions and 5 deletions
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66
share/man/man4/uftdi.4
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@ -29,7 +29,7 @@
.\"
.\" $FreeBSD$
.\"
.Dd March 31, 2014
.Dd August 6, 2015
.Dt UFTDI 4
.Os
.Sh NAME
@ -110,6 +110,11 @@ The
must be one of the
.Va uftdi_bitmodes
values.
Setting
.Va mode
to
.Dv UFTDI_BITMODE_NONE
returns the channel to standard UART mode.
.Bd -literal
enum uftdi_bitmodes
{
@ -139,12 +144,15 @@ and
data which either reflects pin state or is interpreted
as MPSSE commands and parameters, depending on the mode.
.It Dv UFTDIIOC_GET_BITMODE Pq Vt "struct uftdi_bitmode"
Return the state of the bitbang pins at the time of the call in the
Return the current bitbang mode in the
.Va mode
member, and the state of the DBUS0..DBUS7 pins at the time
of the call in the
.Va iomask
member.
The
.Va mode
member is unused.
The pin state can be read while the chip is in any mode, including
.Dv UFTDI_BITMODE_NONE
(UART) mode.
.It Dv UFTDIIOC_SET_ERROR_CHAR Pq Vt int
Set the character which is inserted into the buffer to mark
the point of an error such as FIFO overflow.
@ -164,6 +172,54 @@ This is the
.Va bcdDevice
value from the
.Va usb_device_descriptor .
.It Dv UFTDIIOC_READ_EEPROM Pq Vt "struct uftdi_eeio"
Read one or more words from the configuration eeprom.
The FTDI chip performs eeprom I/O in 16-bit words.
Set
.Va offset
and
.Va length
to values evenly divisible by two before the call, and the
.Va data
array will contain the requested values from eeprom after the call.
.Bd -literal
struct uftdi_eeio
{
uint16_t offset;
uint16_t length;
uint16_t data[64];
};
.Ed
.Pp
The FT232R chip has an internal eeprom.
An external serial eeprom is optional on other FTDI chips.
The eeprom may contain 64, 128, or 256 words,
depending on the part used.
Multiple calls may be needed to read or write the larger parts.
When no eeprom is present, all words in the returned data are 0xffff.
An erased eeprom also reads as all 0xffff.
.It Dv UFTDIIOC_WRITE_EEPROM Pq Vt "struct uftdi_eeio"
Write one or more words to the configuration eeprom.
The
.Va uftdi_eeio
values are as described for
.Dv UFTDIIOC_READ_EEPROM .
.Pp
The FTDI chip does a blind write to the eeprom, and it will appear
to succeed even when no eeprom is present.
To ensure a good write you must read back and verify the data.
It is
.Em not
necessary to erase before writing.
Any position within the eeprom can be overwritten at any time.
.It Dv UFTDIIOC_ERASE_EEPROM Pq Vt int
Erase the entire eeprom.
This is useful primarily for test and debugging, as there is no
need to erase before writing.
To help prevent accidental erasure caused by calling the wrong
ioctl, you must pass the special value
.Dv UFTDI_CONFIRM_ERASE
as the argument to this ioctl.
.El
.Sh HARDWARE
The