1
2
14
15
SIN
SCLK
LAT
BANK_SEL
(Internal bit)
Line Counter
(Internal bit)
WRTGS
GS
Bit 15
GS
Bit 14
GS
Bit 13
3
GS
Bit 2
16
GS
Bit 1
GS
Bit 0
BANK_SEL = 0 (or 1)
Old Line Counter Value
Channel Counter
(Internal bit)
Old Channel Counter Value
GS Counter
(Internal bit)
Old GS Counter Value
Old Channel Counter Value Increased 1
Line Read Counter
(Internal bit)
Old Line Read Counter value
Sub-period Counter
(Internal bit)
Old Sub-period Counter Value
1
2
3
VSYNC
Toggled to 1 (or 0)
Reset to 0
Reset to 0
Reset to 0
Reset to 0
Reset to 0
BANK_SEL is toggled
All Counters are reset to 0
Send VSYNC Command:
Vertical Frame Synchronization (VSYNC)
31
SLVUBF4A – February 2018 – Revised June 2019
Copyright © 2018–2019, Texas Instruments Incorporated
PWM Grayscale Control
TI Information — Selective Disclosure
If the TLC694x device detects three SCLK rising edges during the LAT-signal high period, it considers this
as a vertical frame synchronization command (VSYNC) command (
). All the internal counters are
initialized once the VSYNC command is received.
shows the VSYNC command timing diagram.
Table 3-2. VSYNC Command Description
COMMAND NAME
NUMBER OF SCLK RISING
EDGES WHEN LAT IS
HIGH
DESCRIPTION
VSYNC
3
Vertical frame synchronization command. When this command is received,
BANK_SEL toggles, and all internal counters are reset to 0. A new frame
image is displayed in the coming frame period.
Figure 3-5. Send VSYNC Command
3.2.2 Send VSYNC Command
After all the grayscale (GS) data is written into the selected memory BANK, the external controller sends
the VSYNC command to the TLC694x device. When the VSYNC command is received, the grayscale
data of the memory BANK selected in the previous step is displayed in the coming frame period.
3.3
PWM Control and New Frame Image Display
3.3.1 PWM Control Overview
PWM control means the pulse-width modulation (PWM) control scheme, which controls the turnon ratio of
the output channel OUTn during one display period. The turnon ratio is proportional to the grayscale (GS)
data of this channel. The use of 16-bit GS data per channel results in 65,536 brightness steps, from 0%
up to 100% brightness.
For example:
•
If GS = 0, then OUTn does not turn on during one display period (65,536 GCLK periods, total), and the
brightness ratio is 0%.
•
If GS = 255 (00FFh), then during one display period, OUTn turns on for 255 GCLK periods, and the
brightness ratio is 255 / 65 535 = 0.3891% (Assume 100% brightness if OUTn turns on for 65 535
GCLK periods during one display period).