rp2040

commit a7498c2d173c011455b8bfb0b85f00b23eda532a
parent db25ac26d23f9e898a0807bebc2651b9e3c33314
Author: Matsuda Kenji <info@mtkn.jp>
Date:   Fri, 23 Feb 2024 08:14:20 +0900

count ticks using systick timer

Diffstat:
M
ex3/main.s
 | 
21
++++++++++++++++++++-

1 file changed, 20 insertions(+), 1 deletion(-)
diff --git a/ex3/main.s b/ex3/main.s
@@ -67,6 +67,9 @@ wait_vco:
 	mov r0, #1
 	lsl r0, r0, #11
 	str r0, [r3, #0x48] // CLOCKS: CLK_PERI_CTRL
+	// set clk_ref to xosc
+	mov r0, #2
+	str r0, [r3, #0x30] // CLOCKS: CLK_REF_CTRL
 
 	// setup uart0
 	ldr r3, uart0_base
@@ -85,8 +88,22 @@ wait_vco:
 	ldr r0, =(3 << 5 | 1 << 4) // WLEN = 8, FEN = 1
 	str r0, [r3, #0x2c] // UART: UARTLCR_H
 
+	// set systick timer
+	ldr r3, ppb_base
+	ldr r0, =0xffffff
+	ldr r1, =0xe014
+	str r0, [r3, r1] // M0PLUS: SYST_RVR
+	// enable systick timer
+	sub r1, r1, #4
+	mov r0, #1
+	str r0, [r3, r1] // M0PLUS: SYST_CSR
+
+	mov r4, r3
+	ldr r5, =0xe018
 loop:
-	bl getbyte
+	ldr r0, [r4, r5] // M0PLUS: SYST_CVR
+	bl printh
+	ldr r0, ='\r'
 	bl putbyte
 	b loop
 
@@ -219,3 +236,5 @@ uart0_base:
 	.word 0x40034000
 sio_base:
 	.word 0xd0000000
+ppb_base:
+	.word 0xe0000000