Figure 4-4: Keyboard Scan Codes - evertz 5950-SID Instruction Manual

TECHNICAL DESCRIPTION
Model 5950-SID VITC Reader / Source ID Decoder Manual
LED diagnostics can be invoked by holding down any key on power up.
When any key is pressed, all the front panel LED's should come on. To
exit LED test mode, remove and re-apply power to the unit.
The 10 push buttons are arranged in a 8 x 2 matrix. Data from 8 keys at a
time is latched into U2 by signal SH/LD on U2 pin 1. Address decoder U1
selects which set of 8 switches is latched into U2 using enable lines A0 and
A1. Each time a key is pressed, the MCU firmware generates a key scan
code corresponding to the position of the key in the key matrix.
Keyboard diagnostics can be invoked by pressing any key during power
up. The front panel display will show the message SCAN CODE and the
keyboard scan code. When no keys are depressed, the key scan code is
??. Pressing a key will show the corresponding key scan codes, as shown
in the table below. To exit the keyboard test, remove and re-apply power
to the unit.
Key
TIME/UB
FREEZE
CHAR MODE
CHAR ON/OFF
SELECT

Figure 4-4: Keyboard Scan Codes

4.3.3. High Speed VITC Reader (5200-36) & (5200-34)
Reader composite video is buffered by Q2 and distributed to the VITC sync
separator and data extractor. The sync separator U44 provides H Sync, V
Sync, a Frame pulse (active high for field 1) and a back porch clamp pulse
to drive the DC restorer circuitry U43 and associated components.
Composite video is buffered and DC restored by U43 to provide clamped
VITC video to comparator U45b (test point CRV). Peak detector U45a and
associated components provide a reference level to U45a of approximately
one half the peak VITC level to ensure proper extraction of the VITC data
regardless of the video level. Comparator U45b extracts the VITC data bits
from the video (test point VTCO) and sends it to the LCA U25 for further
processing.
A phase locked loop consisting of U28, 29, and 30 and associated
components extracts the VITC bitrate clock from the data and is used to
decode 0 and 1 bits inside the LCA.
redundancy check (CRC) word and sync bit patterns for the recovered data
and generates a VITC ready signal to the MCU. Data is shifted into U24 or
U26, depending on the reader assignments where it is unloaded by the
MCU. The MCU unloads the VITC data through the LCA.
Scan Code Key
41 SETUP
!
01
"
42
#
02
$
45
The LCA
Scan Code
47
05
06
07
46
validates the cyclic
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