ZHCSAH8B November 2012 – March 2022 TFP401A-Q1
PRODUCTION DATA
The device transmits only one of two possible transition-minimized differential signaling (TMDS) characters for a given pixel at a given time. The transmitter keeps a running count of the number of ones and zeros previously sent, and transmits the character that minimizes the number of transitions to approximate a dc balance of the transmission line.
Reception of RGB pixel data during active display time uses three TMDS channels, DE = high. The same three channels also receive control signals, HSYNC, VSYNC, and user-defined control signals CTL[3:1]. Reception of these control signals occurs during inactive display or blanking-time. Blanking-time is when DE = low. The following table maps the received input data to the appropriate TMDS input channel in a DVI-compliant system.
| RECEIVED PIXEL DATA ACTIVE DISPLAY DE = HIGH | INPUT CHANNEL | OUTPUT PINS (VALID FOR DE = HIGH) |
|---|---|---|
| Red[7:0] | Channel-2 (Rx2 ±) | QE[23:16] QO[23:16] |
| Green[7:0] | Channel-1 (Rx1 ±) | QE[15:8] QO[15:8] |
| Blue[7:0] | Channel-0 (Rx0 ±) | QE[7:0] QO[7:0] |
| RECEIVED CONTROL DATA BLANKING DE = LOW | INPUT CHANNEL | OUTPUT PINS (VALID FOR DE = LOW) |
| CTL[3:2] | Channel-2 (Rx2 ±) | CTL[3:2] |
| CTL[1: 0](1) | Channel-1 (Rx1 ±) | CTL1 |
| HSYNC, VSYNC | Channel-0 (Rx0 ±) | HSYNC, VSYNC |
The TFP401A-Q1 device discriminates between valid pixel TMDS characters and control TMDS characters to determine the state of active display versus blanking, in effect, the state of DE.