<<< :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 MTIME is **not** implemented | Configuration generics: | _IO_MTIME_EN_ | implement MTIME when _true_ | CPU interrupts: | `MTI` | machine timer interrupt (see <<_processor_interrupts>>) |======================= The MTIME module implements a memory-mapped MTIME machine system timer that is compatible to the RISC-V privileged specifications. The 64-bit system time is accessed via the memory-mapped `TIME_LO` and `TIME_HI`registers. A 64-bit time compare register, which is accessible via the memory-mapped `TIMECMP_LO` and `TIMECMP_HI` registers, can be used to configure the CPU's MTI (machine timer interrupt). 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 `TIMECMP` again (either by modifying `TIME` or `TIMECMP`). .Reset [NOTE] After a hardware reset the `TIME` and `TIMECMP` register are reset to all-zero. .External MTIME Interrupt [IMPORTANT] 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 memory-mapped register). All RISC-V standard interrupts can **NOT** be acknowledged by writing zero to the according <<_mip>> CSR bit. + **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 | `0xffffff90` | `NEORV32_MTIME.TIME_LO` | 31:0 | r/w | machine system time, low word | `0xffffff94` | `NEORV32_MTIME.TIME_HI` | 31:0 | r/w | machine system time, high word | `0xffffff98` | `NEORV32_MTIME.TIMECMP_LO` | 31:0 | r/w | time compare, low word | `0xffffff9c` | `NEORV32_MTIME.TIMECMP_HI` | 31:0 | r/w | time compare, high word |=======================