The Z80 was still being used in embedded designs in the 90s. One company I worked at was still supporting Z80 systems and s/w at least until around '94. Possibly later, as I didn't work on those.
In the UK, I never saw a 6809 used in embedded designs (late 80s - mid 90s), I did see plenty of Z80s and 8051 derivatives.
However by that period (late 80s on) a lot of those embedded designs were using NEC V20/V30, as they made for easier systems to program than plain 8bit systems; plus the price range of the systems I had experience with allowed it.
Motorola's embedded cpu's had strange numbers that would make it difficult to recognize to which cpu family it belonged. 68705 were 6800 derived, 68302 were 68000 derived.
As for the 6809 it l ooks like that there were no embedded derivatives of it. 68HC16 seems to be a 16 bit extended 6800 using a similar technic as 65816 to extend the 6502.
NEC V20/V30 not that much but 80186 and all their specialized embedded variants from Intel (80186EA/EB/EC) and AMD (Am186EM) were extremely appreciated as it allowed to use normal MS-DOS compilers and software.
Am186EM we loved that one. 100 pin PQFP with unmultiplexed bus, CMOS up to 40Mhz, including UART, SPI etc.
Yes, AM186EM was doubleplus good. I used it in an early interface between a Kodak DC-20 camera (early digital) and IrDA at high-speed (1 Mb/s in those days).
Also liked the V20/V30 too, built a PC card comm controller with those. You are correct, it was normal to use MS-DOS compilers, although I did have to get a special-purpose debugger (code; interface was uart) for the '186.
With those kinds of products, it's 'annoying' that Intel sort of gave away the embedded space.
(agree: 8051 is high up there in the 'microcontroller' space.)
My first commercial embedded design used a 6809. That was also the last time I ever saw one used in the embedded space! As fun as the 68HC09 was, the 68HC05 and 68HC11 were better choices.
The Z80 was still being used in embedded designs in the 90s. One company I worked at was still supporting Z80 systems and s/w at least until around '94. Possibly later, as I didn't work on those.
In the UK, I never saw a 6809 used in embedded designs (late 80s - mid 90s), I did see plenty of Z80s and 8051 derivatives.
However by that period (late 80s on) a lot of those embedded designs were using NEC V20/V30, as they made for easier systems to program than plain 8bit systems; plus the price range of the systems I had experience with allowed it.