Support for walkera telemetry.

        if (CYRF_ReadDataPacketLen(packet, 0x10)) {
            parse_telemetry_packet(packet);
            delay = 100 * (16 - txState);
            txState = 15;
        }

        // else empty buffer: dummy read all received bytes
        if (length)
            ReadRegisterMulti(CYRF_21_RX_BUFFER, NULL, length);

        // else empty buffer: dummy read all received bytes
        while (length) {
            CYRF_ReadRegister(CYRF_21_RX_BUFFER);
            length--;
        }

static u16 devo_cb()
{
    int delay = 100;
    if (txState == 0) {
        DEVO_BuildPacket();
        CYRF_WriteDataPacket(packet);
        delay = 900;
    } else if (txState == 1) {
        int i = 0;
        u8 reg;
        while ( !((reg = CYRF_ReadRegister(0x04)) & 0x02)) {
            if (++i >= NUM_WAIT_LOOPS)
                break;
        }
        if (((reg & 0x22) == 0x20) || (CYRF_ReadRegister(0x02) & 0x80)) {
     	    CYRF_Reset();
            cyrf_init();
            cyrf_set_bound_sop_code();
            CYRF_ConfigRFChannel(*radio_ch_ptr);
            //printf("Rst CYRF\n");
            delay = 1500;
            txState = 15;
        } else {
            if (state == DEVO_BOUND) {
                /* exit binding state */
                state = DEVO_BOUND_3;
                cyrf_set_bound_sop_code();
            }
            if(pkt_num == 0 || bind_counter > 0) {
                delay = 1500;
                txState = 15;
            } else {
                if (Model.proto_opts[PROTOOPTS_TELEMETRY] == TELEM_ON) {
                    CYRF_SetTxRxMode(RX_EN); //Receive mode
                    CYRF_WriteRegister(CYRF_05_RX_CTRL, 0x80); //Prepare to receive (do not enable any IRQ)
                    delay = 900;
                    txState = 9;
                } else {
                     delay = 1500;
                     txState = 15;
                }
            }
        }
    } else if (txState < 15) {

    txState++;
    if(txState == 16) { //2.3msec have passed
        CYRF_SetTxRxMode(TX_EN); //Write mode
        if(pkt_num == 0) {
            //Keep tx power updated
            CYRF_WriteRegister(CYRF_03_TX_CFG, 0x08 | Model.tx_power);
            radio_ch_ptr = radio_ch_ptr == &radio_ch[2] ? radio_ch : radio_ch_ptr + 1;
            CYRF_ConfigRFChannel(*radio_ch_ptr);
        }
        txState = 0;
    }
    return delay;
}

     } else if(state == DSM2_CH2_READ_A || state == DSM2_CH2_READ_B) {
        //Read telemetry if needed and parse if good
        if (CYRF_ReadDataPacketLen(telem_pkt, 0x10))
            parse_telemetry_packet(telem_pkt);
        else
            CYRF_ReadDataPacketLen(NULL, 0x00);