ZHCSQ95H March 2000 – March 2022 TFP401 , TFP401A
PRODUCTION DATA
TMDS stands for transition-minimized differential signaling. Only one of two possible TMDS characters for a given pixel is transmitted 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.
Three TMDS channels are used to receive RGB pixel data during active display time, DE = high. The same three channels also receive control signals, HSYNC, VSYNC, and user-defined control signals CTL[3:1]. These control signals are received during inactive display or blanking-time. Blanking-time is when DE = low. Table 9-1 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 TFP401/401A discriminates between valid pixel TMDS characters and control TMDS characters to determine the state of active display versus blanking (for example, the state of DE).