MB87P2020 Datasheet, PDF (196/356 Pages) Fujitsu Component Limited. – Colour LCD/CRT/TV Controller

MB87J2120, MB87P2020-A Hardware Manual
Interface to Physical Display
The electrical interface of the actual display wired to the GDC determines the number, type and possibly
the direction of signals at the pins. Direction information is needed for sync signals, as the GPU supports
external and internal synchronization. In case of external synchronization the pins DIS_HSYNC,
DIS_VSYNC, and DIS_VREF are inputs, otherwise outputs.
The digital multi-purpose pins DIS_D[23:0] carry either pixel data or sync signals as given in table 3-14,
section 3.14. Pins not necessary for operation can be switched to high-Z by resetting their corresponding
output enable bit in the DIR_MainEnable word (address 0x3260). This applies also to the color key output
pin DIS_CK as well as to the sync signal pins DIS_HSYNC, DIS_VSYNC, and DIS_VREF when in inter-
nal synchronization mode.
In case of a display with analog inputs connected to GDC the pins A_RED, A_GREEN, and A_BLUE carry
the output if the internal DACs when the following conditions hold (otherwise they are high-Z):
• scan mode (bits [17:16] of DIR_Format) is set to SglScan AND
• DAC output enable as well as reference voltage enable (bits [28] and [29] of DIR_MainEnable,
address 0x3260) is set AND
Either:
— Twin display mode (bit [18] of address 0x3004) is off
— physical color space (bits [3:0] of DIR_Format, address 0x3004) is set to RGB888,
— bit stream format (bits [11:8] of DIR_Format) is set to AN (analog display is primary),
Or (Jasmine only)
— Twin display mode is on
— physical color space is RGB333…RGB888
— bit stream format is set to S9…S24 (analog display is secondary)
When connecting analog displays to GDC via capacitors a clamping value for defined levels is necessary.
This value is entered into the DIR_AClamp register (address 0x3258) and is output during blanking periods.
The similar value DIR_DClamp (address 0x325C) exists for the digital pins and may there be useful for
external glue circuitry.
4.2.2 Values Determined by Application
Matrix Settings (Jasmine only)
If image data is processed in one of the YUV formats appropriate matrix parameters and possibly gamma
table settings are necessary. First, the pre-matrix biases (bits [23:0] of address 0x1400) need be determined.
These are signed 8 bit numbers in 2’s complement which are used to adjust the value ranges of luminance
and chrominance before matrix multiplication. Adjustments should be made in a manner that:
— Luminance (Y) values are mapped to a monotonous range of 0…0xFF (zero to full scale)
— Chrominance (U, V) values are mapped to a monotonous range of 0x80…0…0x7F (most nega-
tive…neutral gray…most positive)
If the image data comply to the ITUR-601 standard then the default values need not be changed.
Next, the matrix coefficients have to be calculated, i.e. their values are mapped to 8 bit binary numbers.
This is accomplished using the following formula:
ConfigReg = abs(Coeff) ⋅ 128 mod 256
(11)
Please be aware that (cf. 3.7.2)
— The absolute value of any coefficient must lie in the range of 0…2
— The values of coefficients CBxG and CRxG (bits [15:8] and [7:0] of address 0x1408)are inter-
nally treated as negative.
If the image data comply to the ITUR-601 standard then the default values need not be changed.
Page 196