# AIC8800DC/DW legacy MCU revision 1 support

The `legacy-mcu1` branch is the maintained compatibility profile for older
AIC8800DC/DW devices tracked in
[issue #71](https://github.com/shenmintao/aic8800d80/issues/71). It follows the
same method as the successful issue #58 D80 profile: use a complete, matched
legacy firmware and loader rather than mixing firmware generations.

The branch keeps the current USB transport, cfg80211 integration, device IDs,
DKMS installer, and modern-kernel compatibility. For AIC8800DC/DW it restores
the complete firmware directory and matching loader from immediately before
SDK V5 commit `d66e5cb`. That loader includes the MCU1 cache fix and flash DPD
validation used by the reporter's previously working driver.

The first issue #71 test proved that the DPD result stored in flash was valid,
but the V5 main application still timed out at `DBG_START_APP_REQ`. Test commit
[`dbfbfa0`](https://github.com/shenmintao/aic8800d80/commit/dbfbfa0) restored the
complete profile matching the reporter's known-good firmware hashes, after
which the reporter confirmed that the TX1U Nano worked.

## Install

```bash
git fetch origin
git switch legacy-mcu1
git pull --ff-only
sudo ./install.sh
sudo poweroff
```

After shutdown, unplug the TX1U Nano or remove host power for at least 10
seconds before reconnecting and booting.

## Verify

```bash
git rev-parse --short HEAD
md5sum /lib/firmware/aic8800DC/fmacfw_patch_8800dc_u02.bin
md5sum /lib/firmware/aic8800DC/fmacfw_patch_tbl_8800dc_u02.bin
lsusb
lsusb -t
iw dev
sudo journalctl -k -b --no-pager | tee issue71-v3-profile.log
sudo journalctl -k -b --no-pager | grep -iE 'issue71|chip_id|chip_mcu_id|chip_sub_id|DPD|calib|patch.*tbl|start app|firmware version|interface|wlan|timed-out|err_lmac'
```

Expected firmware values and log markers include:

```text
bfd8ea1d174242e7ec823813b6c5d849  fmacfw_patch_8800dc_u02.bin
7b5fde609392c2e6c2c5874838dda718  fmacfw_patch_tbl_8800dc_u02.bin
chip_id=7, chip_mcu_id=1, chip_sub_id=1
issue71: using complete pre-SDK-V5/V3 DC/DW firmware and loader profile
issue71: legacy V3 flash DPD result is valid
misc ram valid, skip calib process
FMACFW_PATCH_TBL_8800DC_U02_DESCRIBE_BASE = 187c00
Start app: 00150000, 5
Firmware Version: ...
New interface create wlan0
```

There should be no command timeout, `err_lmac_reqs`, or failed USB probe after
the main application starts.

Confirm scanning, association, DHCP, gateway and Internet reachability, real
traffic, and clean initialization after a USB unplug/replug cycle.

## Roll back

```bash
git switch main
git pull --ff-only
sudo ./install.sh
sudo poweroff
```

Cold-power-cycle the adapter again before booting the rollback result.