jpu_read
int_status = jpu_read(jpu, JINTS);
unsigned long payload_size = jpu_read(jpu, JCDTCU) << 16
| jpu_read(jpu, JCDTCM) << 8
| jpu_read(jpu, JCDTCD);
unsigned char error = jpu_read(jpu, JCDERR) & JCDERR_MASK;
while (jpu_read(jpu, JCCMD) & JCCMD_SRST) {