fix: add tx queue

port/sys_arch.c

@@ -12,7 +12,7 @@ int rand(void) {
 
 void srand(unsigned int seed) { next = seed; }
 
-uint32_t sys_now(void) { return systick_millis; }
+uint32_t sys_now(void) { return millis(); }
 
 sys_prot_t sys_arch_protect(void) {
   unsigned int old_mstatus;