diff --git a/src/main.c b/src/main.c
index 9954cf7..ab9b576 100644
--- a/src/main.c
+++ b/src/main.c
@@ -80,6 +80,7 @@ int main(int argc, char **argv) {
 
     if (strcmp(buffer, "ok") == 0) {
         printf("[mmap]:wr...\n");
+        sleep(1);
         mapped_addr = (volatile uint32_t *)ucp4008_ctrl_mmap_base;
         *mapped_addr = 0xA5A55A5A;
         munmap(ucp4008_ctrl_mmap_base, PAGE_SIZE);