Create bluescsi_timings.ini files for custom SCSI bus timing. Set SpeedGrade=Custom in bluescsi.ini to use.
Advanced Users Only -This tool is intended for testing and debugging SCSI bus timing issues. Incorrect values can cause data corruption, transfer failures, or boot problems on your vintage hardware. All built-in profiles are based on the latest BlueSCSI main branch. If you are not experiencing timing-related issues, the default speed grades in bluescsi.ini are recommended.
PLL
Phase-Locked Loop -hardware clock multiplier that generates the system clock from a 12 MHz crystal
VCO
Voltage-Controlled Oscillator -the high-frequency internal oscillator inside the PLL
cc
Clock Cycles -delay values measured in system clock periods (stored as cycles minus 1 for PIO instruction overhead)
PIO
Programmable I/O -RP2040/RP2350 hardware state machines that drive the SCSI bus and SD card independently of the CPU
ps
Picoseconds -10-12 seconds (1 ns = 1000 ps)
SDIO
SD Input/Output -the 4-bit parallel interface to the SD card
REQ
SCSI Request signal -asserted by the target to initiate each data transfer handshake
sync period
Negotiated SCSI synchronous transfer period, in units of 4 ns (e.g. max_sync=12 means 48 ns minimum period)
Base Speed Grade
Choose a predefined timing profile to extend. Only fields you change will be written to the INI; all others inherit from this base.