i2c_io_req_set_transmit_data
!i2c_io_req_set_transmit_data(req->io_i2c, req->io_wdata,
extern bool i2c_io_req_set_transmit_data(i2c_io_req_t *, const void *, size_t);
if (!i2c_io_req_set_transmit_data(req, wbuf, sizeof (wbuf))) {