<<< :sectnums: ==== Machine System Timer (MTIME) [cols="<3,<3,<4"] [frame="topbot",grid="none"] |======================= | Hardware source file(s): | neorv32_mtime.vhd | | Software driver file(s): | neorv32_mtime.c | | | neorv32_mtime.h | | Top entity port: | `mtime_irq_i` | RISC-V machine timer IRQ if internal one is **not** implemented | | `mtime_time_o` | Current system time (`TIME` register) | Configuration generics: | `IO_MTIME_EN` | implement machine timer when `true` | CPU interrupts: | `MTI` | machine timer interrupt (see <<_processor_interrupts>>) |======================= The MTIME module implements a memory-mapped machine system timer that is compatible to the RISC-V privileged specifications. The 64-bit system time is accessed via individual `TIME_LO` and `TIME_HI` registers. A 64-bit time compare register, which is accessible via individual `TIMECMP_LO` and `TIMECMP_HI` registers, can be used to configure the CPU's machine timer interrupt (`MTI`)). The interrupt is triggered whenever `TIME` (high & low part) is greater than or equal to `TIMECMP` (high & low part). The interrupt remains active (=pending) until `TIME` becomes less than `TIMECMP` again (either by modifying `TIME` or `TIMECMP`). The current system time is available for other SoC modules via the top's `mtime_time_o` signal. .Hardware Reset [NOTE] After a hardware reset the `TIME` and `TIMECMP` register are reset to all-zero. .External MTIME Interrupt [NOTE] If the internal MTIME module is disabled (`IO_MTIME_EN` = `false`) the machine timer interrupt becomes available as external signal. The `mtime_irq_i` signal is level-triggered and high-active. Once set the signal has to stay high until the interrupt request is explicitly acknowledged (e.g. writing to a user-defined memory-mapped register). **Register Map** .MTIME register map (`struct NEORV32_MTIME`) [cols="<3,<3,^1,^1,<6"] [options="header",grid="all"] |======================= | Address | Name [C] | Bits | R/W | Function | `0xfffff400` | `TIME_LO` | 31:0 | r/w | system time, low word | `0xfffff404` | `TIME_HI` | 31:0 | r/w | system time, high word | `0xfffff408` | `TIMECMP_LO` | 31:0 | r/w | time compare, low word | `0xfffff40c` | `TIMECMP_HI` | 31:0 | r/w | time compare, high word |=======================