ST STM32L4+ Series Reference Manual page 917

RM0432
29.8.21 LTDC layer x blending factors configuration register
(LTDC_LxBFCR)
This register defines the blending factors F1 and F2.
The general blending formula is: BC = BF1 x C + BF2 x Cs
•
BC = blended color
• BF1 = blend factor 1
•
C = current layer color
•
BF2 = blend factor 2
•
Cs = subjacent layers blended color
Address offset: 0xA0 + 0x80 * (x - 1), (x = 1 to 2)
Reset value: 0x0000 0607
31 30 29 28
Res. Res. Res. Res.
15 14 13 12
Res. Res. Res. Res.
Bits 31:11 Reserved, must be kept at reset value.
Bits 10:8 BF1[2:0]: blending factor 1
These bits select the blending factor F1.
000: reserved
001: reserved
010: reserved
011: reserved
100: constant alpha
101: reserved
110: pixel alpha x constant alpha
111: reserved
Bits 7:3 Reserved, must be kept at reset value.
Bits 2:0 BF2[2:0]: blending factor 2
These bits select the blending factor F2
000: reserved
001: reserved
010: reserved
011: reserved
100: reserved
101: 1 - constant alpha
110: reserved
111: 1 - (pixel alpha x constant alpha)
27 26 25 24
Res. Res. Res. Res.
11 10 9 8
Res. BF1[2:0]
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RM0432 Rev 6
LCD-TFT display controller (LTDC)
23 22 21 20
Res. Res. Res. Res.
7 6 5 4
Res. Res. Res. Res.
19 18 17 16
Res. Res. Res. Res.
3 2 1
Res. BF2[2:0]
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