diff options
Diffstat (limited to 'software/first')
| -rw-r--r-- | software/first/first.c | 1 | ||||
| -rw-r--r-- | software/first/memory_map.inc | 1 | ||||
| -rw-r--r-- | software/first/setup_timer_irq.S | 34 | ||||
| -rw-r--r-- | software/first/super_blink.h | 1 |
4 files changed, 37 insertions, 0 deletions
diff --git a/software/first/first.c b/software/first/first.c index ede96db..7505d6c 100644 --- a/software/first/first.c +++ b/software/first/first.c @@ -14,6 +14,7 @@ int main() { }; setup_GPIO(); + setup_timer_irq(); while (!error) { set_LED(colours[ledNum], ON); diff --git a/software/first/memory_map.inc b/software/first/memory_map.inc index e28af43..b532fee 100644 --- a/software/first/memory_map.inc +++ b/software/first/memory_map.inc @@ -1,3 +1,4 @@ .equ GPIO_CTRL_ADDR, 0x10012000 .equ MTIME, 0x0200BFF8 +.equ MTIMECMP, 0x02004000 .equ MTIME_FREQUENCY, 33 diff --git a/software/first/setup_timer_irq.S b/software/first/setup_timer_irq.S new file mode 100644 index 0000000..4ae714f --- /dev/null +++ b/software/first/setup_timer_irq.S @@ -0,0 +1,34 @@ +.section .text +.align 2 +.global setup_timer_irq +.include "memory_map.inc" + +setup_timer_irq: + addi sp, sp, -16 # Allocate stack frame + sw ra, 12(sp) # save return address to the stack + + lw t0, irq_handler # load address of irq_handler + slli t0, t0, 1 # shift address left by one; LSB will be 0 which is direct mode (what we want) + csrw mtvec, t0 # write handler address and mode + + # Here we cannot use csrsi because it can only set up to 5 bits + li t0, 0x80 # set 7th bit (indexed from 0) + csrw mie, t0 # activate machine timer interrupt + + # write high value to the timercmp just to be sure we don't + # trigger an interrupt by mistake + li t0, 0x7FFFFFFF # high number + li t1, 0xFFFFFFFF # high number + li t2, MTIMECMP # load address of timecmp register + sw t0, 4(t2) # store the first number to the upper part first + sw t1, 0(t2) # then the second to the lower part + + csrsi mstatus, 0x4 # set 3rd bit to activate machine interrupts. + + lw ra, 12(sp) # load return address + addi sp, sp, 16 # deallocate stack frame + ret + + +irq_handler: + mret diff --git a/software/first/super_blink.h b/software/first/super_blink.h index 74cc00a..b53d55d 100644 --- a/software/first/super_blink.h +++ b/software/first/super_blink.h @@ -9,4 +9,5 @@ void setup_GPIO(); int set_LED(int color, int state); +void setup_timer_irq(); void delay(int milliseconds); |