The TI ACX100/ACX111 is a already somewhat outdated 802.11 wireless LAN chipset, which is based on a ARM7TDMI core. There is an open source project which develops a Linux kernel driver.

For a full list of devices see here.

When taking apart a Level1 WBR-2401B router, I noticed that the used ACX100 CardBus-card has a 6-pin header.

As it turned out by try and error, it is connected to the JTAG pins of the ACX100 chip. Once it was clear that the first 2 pins are GND and VDD (+3.3V), I tried all combinations of the JTAG signals.