what's shift clock

Started by leilei December 28, 2008
hi, when i read rtl8139 driver's source, there's a macro like this:
#define EE_SHIFT_CLK	0x04	/* EEPROM shift clock. */
the comment say it is a eeprom shift clock.
can any one tell me what is shift clock.and what it is used to do?
leilei wrote:
> hi, when i read rtl8139 driver's source, there's a macro like this: > #define EE_SHIFT_CLK 0x04 /* EEPROM shift clock. */ > the comment say it is a eeprom shift clock. > can any one tell me what is shift clock.and what it is used to do?
My first thought is that it is an I/O port bit mask for a clock line for an interface to a serial EEPROM. How is it used? -- Thad
On Dec 28, 4:05=A0am, leilei <huxuelei...@gmail.com> wrote:
> hi, when i read rtl8139 driver's source, there's a macro like this: > #define EE_SHIFT_CLK =A0 =A00x04 =A0 =A0/* EEPROM shift clock. */ > the comment say it is a eeprom shift clock. > can any one tell me what is shift clock.and what it is used to do?
Hi Serial EEPROMs have no normal clock reference. They have a serial data in, shift clock and data out. The shift clock is used to shift the serial bits in and out. One would provide a bit on the serial in and then toggle the shift clock. One could then look at the serial out bit or repeat. Look at one of the specs for a serial EEPROM. Dwight
On Dec 28, 6:05=A0am, leilei <huxuelei...@gmail.com> wrote:
> hi, when i read rtl8139 driver's source, there's a macro like this: > #define EE_SHIFT_CLK =A0 =A00x04 =A0 =A0/* EEPROM shift clock. */ > the comment say it is a eeprom shift clock. > can any one tell me what is shift clock.and what it is used to do?
Look up "synchronous serial". I wouldn't be surprised if Wikipedia has a decent entry. JM
On Dec 28, 2:18 pm, Thad Smith <ThadSm...@acm.org> wrote:
> leilei wrote: > > hi, when i read rtl8139 driver's source, there's a macro like this: > > #define EE_SHIFT_CLK 0x04 /* EEPROM shift clock. */ > > the comment say it is a eeprom shift clock. > > can any one tell me what is shift clock.and what it is used to do? > > My first thought is that it is an I/O port bit mask for a clock line for > an interface to a serial EEPROM. How is it used? > > -- > Thad
You are correct, Thad. Very obvious from just a quick glance at the code. AL
LittleAlex wrote:
> On Dec 28, 2:18 pm, Thad Smith <ThadSm...@acm.org> wrote: >> leilei wrote: >>> hi, when i read rtl8139 driver's source, there's a macro like this: >>> #define EE_SHIFT_CLK 0x04 /* EEPROM shift clock. */ >>> the comment say it is a eeprom shift clock. >>> can any one tell me what is shift clock.and what it is used to do? >> >> My first thought is that it is an I/O port bit mask for a clock line >> for an interface to a serial EEPROM. How is it used? >> >> -- >> Thad > > You are correct, Thad. > > Very obvious from just a quick glance at the code.
I gave the OP basically the same answer two weeks ago (16 Dec) and even explained the code segment they posted that clocks out the data one bit at a time. I then advised them to look at SPI communications. It appears that the OP only cares to worry about this problem once per week.
On 31/12/2008 Anthony Fremont wrote:

> LittleAlex wrote: > >On Dec 28, 2:18 pm, Thad Smith <ThadSm...@acm.org> wrote: > > > leilei wrote: > > > > hi, when i read rtl8139 driver's source, there's a macro like > > > > this: #define EE_SHIFT_CLK 0x04 /* EEPROM shift > > > > clock. */ the comment say it is a eeprom shift clock. > > > > can any one tell me what is shift clock.and what it is used to > > > > do? > > > > > > My first thought is that it is an I/O port bit mask for a clock > > > line for an interface to a serial EEPROM. How is it used? > > > > > > -- > > > Thad > > > > You are correct, Thad. > > > > Very obvious from just a quick glance at the code. > > I gave the OP basically the same answer two weeks ago (16 Dec) and > even explained the code segment they posted that clocks out the data > one bit at a time. I then advised them to look at SPI > communications. It appears that the OP only cares to worry about > this problem once per week.
I guess it takes him that long to read the next page of the data sheet. -- John B