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by jremington
Mon Jul 26, 2021 7:43 pm
Forum: General discussion
Topic: STM32F746 Discovery tft "draw pixel" problems
Replies: 7
Views: 2703

Re: STM32F746 Discovery tft "draw pixel" problems

I think the problem is in the HAL driver and/or display hardware. It works fine to display bitmaps and text, though.

I abandoned the STM32F746 Discovery for this project. The Teensy 3.2 processor and a 3.5" tft display does what I want.
by jremington
Mon Jul 26, 2021 2:46 pm
Forum: General discussion
Topic: STM32F746 Discovery tft "draw pixel" problems
Replies: 7
Views: 2703

Re: STM32F746 Discovery tft "draw pixel" problems

Thanks for the response. As stated in the most recent post, use of the delay function is not the problem. A nonblocking approach using micros() shows exactly the same behavior as a blocking approach. No method I've been able to come up with allows display of randomly placed dots on the screen, slowl...
by jremington
Sun Jul 25, 2021 4:00 pm
Forum: General discussion
Topic: STM32F746 Discovery tft "draw pixel" problems
Replies: 7
Views: 2703

Re: STM32F746 Discovery tft graphics library issue

Well, the "draw hesitation" has nothing to do with the core function delayMicroseconds(). Here I replaced the call to delayMicroseconds() with a call to a function consisting of a "do nothing" loop written in assembly code. Same bizarre behavior, of pixels getting skipped, then f...
by jremington
Sun Jul 25, 2021 3:32 pm
Forum: General discussion
Topic: STM32F746 Discovery tft "draw pixel" problems
Replies: 7
Views: 2703

Re: STM32F746 Discovery tft graphics library issue

Some progress was made by using delayMicroseconds() instead of delay(). Now, no pixels are skipped permanently, only transiently. But the "draw" behavior clearly shows buffering of the graphics actions, as pixels initially skipped are filled in after an indeterminate pause. I don't underst...
by jremington
Sun Jul 25, 2021 3:37 am
Forum: General discussion
Topic: STM32F746 Discovery tft "draw pixel" problems
Replies: 7
Views: 2703

STM32F746 Discovery tft "draw pixel" problems

Hi, All: I have run across a non-deterministic problem that may be due to an interaction between the display hardware access and program writes to RAM. I'm using the LTDC lib associated with this branch of the core: https://github.com/fpistm/Arduino_Core_ ... TEST_1.9.0 UPDATED PROBLEM SUMMARY: in c...
by jremington
Wed Jul 14, 2021 1:39 am
Forum: Libraries & Hardware
Topic: STM32F746_Discovery: bug in touch screen library?
Replies: 2
Views: 3818

Re: STM32F746_Discovery: bug in touch screen library?

Problem solved! I discovered that clearing the screen overwrote some critical program variable. The issue was resolved by specifically declaring the screen buffer as a global variable. Evidently malloc() does not properly observe some heap or stack boundary of program ram usage. Fix: don't use mallo...
by jremington
Sun Jul 26, 2020 12:20 am
Forum: Libraries & Hardware
Topic: STM32F746_Discovery: bug in touch screen library?
Replies: 2
Views: 3818

STM32F746_Discovery: bug in touch screen library?

The TS library appears to perform unexpected, unauthorized writes to at least two distinct RAM memory locations, when the first call to .getPoint() is executed. I'm using this branch of the 1.9.0 core: https://github.com/fpistm/Arduino_Core_STM32/tree/LTDC_TS_TEST_1.9.0 The offending code is the unm...
by jremington
Thu Jun 18, 2020 5:21 pm
Forum: General discussion
Topic: How to install particular branch of STM32 core?
Replies: 4
Views: 3752

Re: How to install particular branch of STM32 core?

That worked perfectly. Thanks very much!!

Please consider adding those instructions to the Wiki, for GitHub-ignorant Windows users like myself.
by jremington
Thu Jun 18, 2020 3:46 pm
Forum: General discussion
Topic: How to install particular branch of STM32 core?
Replies: 4
Views: 3752

Re: How to install particular branch of STM32 core?

Thanks, I tried to follow those instructions (quote below), but they don't work on Windows. 3.1. Cloning the git repository to replace the stm32 core version package (1st method) In the "<local Arduino directory>/packages/STM32/hardware/stm32/" do the clone: git clone https://github.com/st...
by jremington
Thu Jun 18, 2020 3:04 pm
Forum: General discussion
Topic: How to install particular branch of STM32 core?
Replies: 4
Views: 3752

How to install particular branch of STM32 core?

Hi, All: I have the STM32F7456G Discovery board and would like to use the TFT display. I've gone through the standard procedure of installing the master branch of STM32 core, which works fine for a Blink program, but does not have the display enabled. Using Windows 10 and Arduino IDE 1.8.12 So, I re...

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