In industrial equipment, high FPS or complex animations are rarely required. Instead, the critical necessity is the reliable display of real-time process parameters with minimal impact on the main program loop. The display must function as an autonomous information node, meaning its updates should neither impose parasitic overhead on the CPU's computational resources nor rely on blocking functions.
Connecting the GMG12864-06 (ST7565R) display to an STM32 microcontroller introduces a synchronization issue between the A0 (Command/Data) pin and the hardware SPI. Due to the STM32's hardware FIFO buffer, the processor considers the transmission complete before the data byte actually leaves the bus. If the A0 or CS pin is toggled immediately after the transmit function call, the display interprets the trailing bits of a command as data (or vice versa), which corrupts the initialization sequence and causes visual artifacts on the screen.
To prevent this, the software must explicitly poll the SPI busy flag (BSY). However, this busy-waiting loop blocks execution and wastes CPU clock cycles.
To resolve this issue, I intend to implement an efficient, non-blocking display output pipeline. Utilizing DMA with Request Synchronization mode will fully automate the page-addressing and line-switching sequences, completely offloading the core during the frame transmission. Leveraging the cutting-edge architecture of the NUCLEO-C5A3ZG, the synchronization of the A0 line is designed to be handled asynchronously, completely eliminating blocking CPU cycles. Implementing this approach transforms the display update into a fully background process, where the microcontroller core only initiates the transmission of a ready frame. This guarantees zero blocking of critical industrial automation tasks.
Consequently, the design shifts from relying on off-the-shelf application libraries to implementing a custom low-level driver integrated directly into the microcontroller's hardware logic.