XJ128 and XJ128 Plus Printhead
XJ128 Guide to Operation
Xaar Document no: D031010302 Version A
Page 33
For printheads the print data (a
“
1
”
is eject droplet and a
“
0
”
is do not eject droplet) is only
loaded through data input signal MOSI.
Data for one pixel line is loaded by a sequence of two 64-bit load operations. The
‘
data strobe
’
(SCK)
clock is used to clock data into the shift register on the rising edge. The nSS(x) signal should be
pulled low to enable the target chip to load the new print data.
The shift register is double buffered, allowing the loading of the next line of print data whilst the
current line is being printed. Data may be loaded into the shift register when the READY signal has
switched to the inactive state. During this time, the printhead could be printing the first line of data.
Once all the pixel data has been loaded, the nFIRE signal is triggered to
‘
fire
’
the loaded data as
droplets. It is important that input PHO is stable before nFIRE is triggered. nFIRE ensures that all
three cycles (A, B and C) are printed with a fixed time period between each cycle.
As the printhead starts firing the
‘
C
-cycle
’
of the loaded data, the READY signal switches to the
inactive state.
Figures 6.4 and 6.5 show the data load sequence and timing for all models of the XJ128 printhead.
The timings of these signals shown are tabulated in table 6.12.
Figure 6.4
–
XJ128 print data loading and control signals
Figure 6.5
–
Further timings for XJ128 control signals
