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| author | Jacques Comeaux <jacquesrcomeaux@protonmail.com> | 2024-05-20 23:19:14 -0500 |
|---|---|---|
| committer | Jacques Comeaux <jacquesrcomeaux@protonmail.com> | 2024-05-20 23:19:14 -0500 |
| commit | 7388c270069c2d1418539bca1d2789a6d468ecc2 (patch) | |
| tree | d3848031f6c2d4d45ec0a7c75b12a9f476680726 /setup/xosc.s | |
| parent | 7f47fc894d43739fb0107fd17e76f65ae2bf46bc (diff) | |
Make shared object for setup routines
Diffstat (limited to 'setup/xosc.s')
| -rw-r--r-- | setup/xosc.s | 23 |
1 files changed, 23 insertions, 0 deletions
diff --git a/setup/xosc.s b/setup/xosc.s new file mode 100644 index 0000000..63760da --- /dev/null +++ b/setup/xosc.s @@ -0,0 +1,23 @@ +.syntax unified +.cpu cortex-m0plus +.thumb + +.equ XOSC_BASE, 0x40024000 +.equ CTRL_OFST, 0x0 +.equ STATUS_OFST, 0x4 +.equ STARTUP_OFST, 0xc + +.type start_xosc, %function +.global start_xosc + +start_xosc: + ldr r1, =XOSC_BASE + movs r0, 47 // startup delay for 12Mhz crystal + str r0, [r1, STARTUP_OFST] + ldr r0, =0x00fabaa0 // enable + str r0, [r1, CTRL_OFST] +1: + ldr r0, [r1, STATUS_OFST] + lsrs r0, 31 // stable bit + beq 1b + bx lr |