Faster Startup Graphics for Raspberry Pi Handhelds

Raspberry Pi's latest firmware beta enables custom splash screens for SPI and I2C displays during early boot sequences, addressing demand from handheld computing projects like the M5Stack Cardputer Zero. The solution implements a specialized language compiler within the bootloader for display initialization, reducing boot-to-splash time to approximately two seconds. Developers can configure display parameters through a syntax inspired by Noralf Trønnes' mipi-dbi language, modified to support I2C interfaces and static image compilation. The implementation includes examples for seven-segment displays and demonstrates protocol flexibility - including an SPI-to-UART workaround for receipt printer control. The feature, currently in beta, requires firmware updates through raspi-config's Advanced Settings menu. Custom splash binaries must be placed in the boot firmware folder with config.txt modifications. While primarily targeting handheld implementations using small SPI/I2C displays, the system maintains compatibility with Linux mipi-dbi drivers for broader application support. This development responds to growing use of Raspberry Pi in cyberdeck and portable computing projects demanding faster visual feedback during startup. Early testing utilized an M5Stack Cardputer Zero prototype to validate responsiveness improvements, though the solution applies generally to compatible SPI/I2C display interfaces.