2014-11-26 10:13 AM
I am going to use STM32F429 to control the LCD with 800*600 resolution. The datasheet shows STM32F4 has an integrated LCD controller. Anyone can tell me how to use that controller to drive the LCD without adding extra LCD controller?
#freq #tft-ltdc-stm32f429-color-format #ltdc #stm32f4292014-11-26 01:45 PM
Have a look at the '429 DISCOVERY for an example.
JW2014-11-27 05:51 PM
Hi all,
I've inquired a free STM32F429ZI sample for driving a 10'' LCD supporting XGA 1024*768 with 65MHz refresh rate. In the STM32F429ZI datasheet, it describes that LTDC clock output frequency is 42MHz. And then I use STM32CubeMX to configure parameters, but it's possible to set LCD-TFT clocks 65.x MHz. It confuses me!! About the configuration of STM32CubeMX, is it a correct, a bug or anything else? Hope anyone can help me. Best Regards, Louis Lee2014-11-27 06:30 PM
I'd imagine it's Cube's failure to adequately scope the variables. I'd suspect the number is between 42-45 MHz depending on the SDRAM speed (84/90MHz) and that of the processor (168/180MHz)
Suggest you inquire with an FAE as to the hardware limits, and to the appropriate forum for Cube bugs.2014-11-28 10:44 AM
I think all depends on the color scheme: if using 1byte/pixel (e.g. L8: 256 colors with CLUT), the 65MB/s bandwidth is easily accessible by 16 or 32bit FCM external memory access. 2byte/pixel (e.g. RGB5-6-5 color format) is still reachable: 130MB/s-> 33MHz/32bit at external SRAM or SDRAM.
2014-11-28 11:40 AM
The poster did quote MHz, and it's not uncommon for those size panels to push 170-230 MBps at the probable colour depths in use here, with a clock of 65 MHz
I'd expect the STM32 to need a panel with a lower refresh rate to get the clocks reined in sufficiently. ST staff very may well have a list of known-to-work panels.