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STM32F429 - LTDC Display Size Limit

Question asked by Daemy on Oct 13, 2016
Latest reply on Oct 13, 2016 by Daemy
STM32F429 - LTDC Display Size Limit


The data sheet for the STM32F429 describes the maximum pixel with of the LTDC as 1204 pixels.
However,.. other than CubeMX not allowing the value entered for display width, to be > 1024, I can’t see any reason from the data sheet / reference manual why it can’t be programmed to be greater (e.g. 1280 pixels)


I want to interface a 1280 x120 pixel LCD to an STM32F429
LCD horizontal parameters:
H_Sync = 3
HBP = 54
Active Width = 1280
HFP = 54


As I see it,.


Programming the (horizontal aspects of the) LTDC controller is done via 4 registers.


LTDC_SSCR = HSYNC Width(-1)          
LTDC_BPCR = HSYNC Width + HBP(-1)
LTDC_AWCR = HSYNC Width + HBP +Active Width(-1)
LTDC_TWCR = HSYNC Width + HBP + Active Width + HFP(-1)


The active (display) width of the display being the difference between TDC_AWCR & LTDC_BPCR


None of the limits of the programmable values for these register seems to preclude and active width of 1280 pixels.


The horizontal values for the window mapped onto the display are programmed in LTDC_LxWHPCR and appear to be 12 bits wide (i.e. values of 0-4095)
WHSTPOS[11:0]: Window Horizontal Start Position
WHSPPOS[11:0]: Window Horizontal Stop Position
Thus allowing in theory a window up to 4096 pixels wide


Again, nothing there appears to preclude a window width of 1280 pixels.


Unfortunately to try it out will cost me ~ £160 for the display & the time & effort to build a patch for the connection to my hardware, so to save the cost / hassle, only to fail, I’d love someone either tell me if I'm wrong & why, or confirm it is possible.


Thanks in advance

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