static FT_TRANSFER_AREA *transfer_area = NULL;
-static char pwm[8] = {0};
-static char pwm_next[8] = {0};
+static int8_t pwm[8] = {0};
+static int8_t pwm_next[8] = {0};
static pthread_mutex_t pwm_mutex = PTHREAD_MUTEX_INITIALIZER;
void cb_set_output(const ::roboint::OutputConstPtr& msg) {