GRTS_CH_Z1
error = grts_map_channel(st, dev, GRTS_CH_Z1, "z1", true);
if (st->ch_map[GRTS_CH_Z1] >= GRTS_MAX_CHANNELS)
} else if (st->ch_map[GRTS_CH_Z1] < GRTS_MAX_CHANNELS) {
unsigned int z1 = touch_info[st->ch_map[GRTS_CH_Z1]];