125 lines
6.0 KiB
C
125 lines
6.0 KiB
C
// #################################################################################################
|
|
// # << NEORV32 - RISC-V Machine Timer (MTIME) Demo Program >> #
|
|
// # ********************************************************************************************* #
|
|
// # BSD 3-Clause License #
|
|
// # #
|
|
// # Copyright (c) 2023, Stephan Nolting. All rights reserved. #
|
|
// # #
|
|
// # Redistribution and use in source and binary forms, with or without modification, are #
|
|
// # permitted provided that the following conditions are met: #
|
|
// # #
|
|
// # 1. Redistributions of source code must retain the above copyright notice, this list of #
|
|
// # conditions and the following disclaimer. #
|
|
// # #
|
|
// # 2. Redistributions in binary form must reproduce the above copyright notice, this list of #
|
|
// # conditions and the following disclaimer in the documentation and/or other materials #
|
|
// # provided with the distribution. #
|
|
// # #
|
|
// # 3. Neither the name of the copyright holder nor the names of its contributors may be used to #
|
|
// # endorse or promote products derived from this software without specific prior written #
|
|
// # permission. #
|
|
// # #
|
|
// # THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS #
|
|
// # OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF #
|
|
// # MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE #
|
|
// # COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, #
|
|
// # EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE #
|
|
// # GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED #
|
|
// # AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING #
|
|
// # NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED #
|
|
// # OF THE POSSIBILITY OF SUCH DAMAGE. #
|
|
// # ********************************************************************************************* #
|
|
// # The NEORV32 Processor - https://github.com/stnolting/neorv32 (c) Stephan Nolting #
|
|
// #################################################################################################
|
|
|
|
|
|
/**********************************************************************//**
|
|
* @file demo_mtime/main.c
|
|
* @author Stephan Nolting
|
|
* @brief Simple machine timer (MTIME) usage example.
|
|
**************************************************************************/
|
|
|
|
#include <neorv32.h>
|
|
|
|
|
|
/**********************************************************************//**
|
|
* @name User configuration
|
|
**************************************************************************/
|
|
/**@{*/
|
|
/** UART BAUD rate */
|
|
#define BAUD_RATE 19200
|
|
/**@}*/
|
|
|
|
|
|
// Prototypes
|
|
void mtime_irq_handler(void);
|
|
|
|
|
|
/**********************************************************************//**
|
|
* This program blinks an LED at GPIO.output(0) at 1Hz using the machine timer interrupt.
|
|
*
|
|
* @note This program requires the MTIME unit to be synthesized (and UART0 and GPIO).
|
|
*
|
|
* @return Should not return;
|
|
**************************************************************************/
|
|
int main() {
|
|
|
|
// capture all exceptions and give debug info via UART
|
|
neorv32_rte_setup();
|
|
|
|
// setup UART at default baud rate, no interrupts
|
|
neorv32_uart0_setup(BAUD_RATE, 0);
|
|
|
|
|
|
// check if MTIME unit is implemented at all
|
|
if (neorv32_mtime_available() == 0) {
|
|
neorv32_uart0_puts("ERROR! MTIME timer not implemented!\n");
|
|
return 1;
|
|
}
|
|
|
|
// Intro
|
|
neorv32_uart0_puts("RISC-V Machine System Timer (MTIME) demo Program.\n"
|
|
"Toggles GPIO.output(0) at 1Hz using the RISC-V 'MTI' interrupt.\n\n");
|
|
|
|
|
|
// clear GPIO output port
|
|
neorv32_gpio_port_set(0);
|
|
|
|
|
|
// install MTIME interrupt handler to RTE
|
|
neorv32_rte_handler_install(RTE_TRAP_MTI, mtime_irq_handler);
|
|
|
|
// configure MTIME timer's first interrupt to appear after SYSTEM_CLOCK / 2 cycles (toggle at 2Hz)
|
|
// starting from _now_
|
|
neorv32_mtime_set_timecmp(neorv32_mtime_get_time() + (NEORV32_SYSINFO->CLK / 2));
|
|
|
|
// enable interrupt
|
|
neorv32_cpu_csr_set(CSR_MIE, 1 << CSR_MIE_MTIE); // enable MTIME interrupt
|
|
neorv32_cpu_csr_set(CSR_MSTATUS, 1 << CSR_MSTATUS_MIE); // enable machine-mode interrupts
|
|
|
|
|
|
// go to sleep mode and wait for interrupt
|
|
while(1) {
|
|
neorv32_cpu_sleep();
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
|
|
/**********************************************************************//**
|
|
* MTIME IRQ handler.
|
|
*
|
|
* @warning This function has to be of type "void xyz(void)" and must not use any interrupt attributes!
|
|
**************************************************************************/
|
|
void mtime_irq_handler(void) {
|
|
|
|
// update MTIMECMP value for next IRQ (in SYSTEM_CLOCK / 2 cycles)
|
|
// this will also ack/clear the current MTIME interrupt request
|
|
neorv32_mtime_set_timecmp(neorv32_mtime_get_timecmp() + (NEORV32_SYSINFO->CLK / 2));
|
|
|
|
|
|
neorv32_uart0_putc('.'); // send tick symbol via UART
|
|
neorv32_gpio_pin_toggle(0); // toggle output port bit 0
|
|
}
|