The least significant 8 bits of the pixel are connected to the
Master device and the most significant 8 bits are connected to the
device producing the final result.. The internal sum in this device
must be delayed by four pixels to match the delay in the
expansion output from the first device. This is actually achieved
by delaying the pixel inputs to the line stores (register D, bits 4:2,
= 001). The expansion input needs no additional delay (register
D, bits 1:0, = 10).
The actual pixel precision can be any number of pixels
between 8 and 16, and may be a signed or unsigned number. Any
unused, more significant bits, must respectively be either sign
extended or be tied low.
second row must be delayed by 8 clock cycles (register D, bits
3:2, = 10). The DELOP output needs twelve additional clock
delays to match the processing delay.
Figs. 16 and 17 show non-interlaced and interlaced versions
of the above 838 and 434 arrangements
Fig. 18 shows how four devices can also be used to provide
an 838 window, with 16-bit pixels and 20MHz clock rates. The
expansion data from a previous device needs no additional delay
since the partial window size in each device is only 434. The
internal convolver sums from third and fourth devices must be
delayed by 8 clocks and the DELOP output must have 12
additional delays. If this arrangement is to be used in a non-
interlaced application, the field store must be replaced by four line
delays.
DELOP must have four additional pipeline delays in order to
match the total processing delay. This output can be obtained
from either device.
Six device systems
Four device systems
As shown in Fig. 19, six devices, each in an 8W34D mode
using 8-bit pixels, can provide a 16W312D window at 20MHz
clock rates. Expansion inputs from previous devices in a row (but
not the first device in each row) need an extra 4 clocks of delay
since the partial window is eight pixels wide. Internal convolver
sums need a differential delay of 12 clock cycles from row to row
(register D, bits 3:2, = 11).
Four devices, each in the 838 mode, can be used to provide
a 16316 window, with 8-bit pixel resolution and 10MHz clock
rates. The partial sum from the first device in each row must be
delayed by eight pixel clocks before it is added to the result from
the next device. This provides the eight pixel displacement to
match the width of the window. The delay is actually provided by
four additional delays in the expansion input to the next device,
plus the inherent four clock delays in outputting results from the
first device. Register D, bit 0 controls the additional delay.
The internal convolver sums, in the two devices in the second
row, must be delayed by 12 clocks before they are added to the
result from the first row. This twelve clock delay is necessary
because of the combination of the eight pixel horizontal displace-
ment delay, and the four clock delay in outputting the result from
the last device in the top row. It is actually achieved by delaying
the pixel inputs to the line stores (register D, bits 3:2, = 11).
The DELOP output must have 20 delays additional to those
in a single device. This compensates for the twelve delays added
to the convolver sums in the second row, plus an additional eight
delays to compensate for the partial width of the first device in the
second row.
The DELOP output must have 32 additional delays to match
the total processing delay.
Eight device systems
Two additional chips will extend the above six device configu-
ration to a 16316 window. Internal convolver sums must have
differential delays of 12 clock cycles between rows, as in the six
device system. The DELOP output needs 44 additional clock
delays.
Nine device systems
Nine devices each in the 838 mode will provide a 24324
window with 8- bit data and 10MHz pixel clocks. This is
shown in Fig. 20. Expansion data inputs from previous
devices in a row (but not the first device in each row) need
an extra 4 clocks of delay, controlled by register D, bit 0 The
internal convolver sums need differential delays of 20 clock
cycles between rows. Sixteen of the latter delays can be
provided internally by setting register B, bit 3 and also
register D, bits 3:2. The four extra delays must be provided
externally.
Four devices can also be used to give an 838 window, but
with a 30MHz pixel clock. Each device is configured to provide
a 434 partial window, but the maximum pixel rate is reduced from
40 to 30MHz because of the response of the line delay expansion
circuitry. Intermediate precision is restricted to 16 bits, since time
multiplexed data outputs cannot be used above 20MHz.
This configuration requires no additional delay in the expan-
sion inputs, and the inputs to the line stores both devices in the
The DELOP output needs 56 clock delays in addition to
the 29 required for the 838 single device configuration.
22
MITEL [ MITEL NETWORKS CORPORATION ]
