[sdiy] HMI-200 8051 ICE Ext. Clk

[Barry Klein]

Too long ago for me to remember but having lunch today with an engineer that used it quite a bit in the early 90's(?) if he remembers I'll let you know. In the meantime I found this about another emulator:
It is dissuaded to use a crystal in the target as a clock source during the emulation. It is recommended that the oscillator be used instead. Normally, a crystal and two capacitors are connected to the CPU's clock inputs in the target application as stated in the CPU datasheets. A length of clock paths is critical and must be taken into consideration when designing the target. During the emulation, the distance between the crystal in the target and the CPU (on the POD) is furthermore increased; therefore the impedance may change in a manner that the crystal doesn't oscillate anymore. In such case, a standalone crystal circuit, oscillating already without the CPU must be built or an oscillator must be used. 


Barry

> On Oct 11, 2016, at 8:52 PM, Tony K <weplar at gmail.com> wrote:
> 
> Hi there folks, time for me to ask for help this time.
> 
> I recently revisited my old 8051 music development projects and have never tried using the targets external clock but used the ICE's internal 16 MHz clock. This has been okay for things up to now but for s/w timing loops and such of course this is unacceptable. Basically the problem is the emulator software - and I have the Huntsville DOS , 16 and 32 bit software running on a slow serial port (38400 max) - crashes or times out when I set ext. clk in the configuration page. Always works with it's internal clock.
> 
> The test target was the Jupiter-6's own 12 Mhz oscillator which is 'double buffered' before going to the slave voice micros. Another question I had was how do you get these emulators to work with targets that use crystals or ceramic resonators and the internal 8051 oscillator ? It seems that would be obvious oversight. The documentation is of no help.. well maybe a little.
> 
> My dev system consists if an MMT-8, an Eprom Emulator and this ICE I acquired recently and had tried it with the MMT-8.
> 
> Sorry if any of this is confusing. 
> This is am older Huntsville Microsystems 8051 ICE, very powerful but slow (38400 baud) !
> 
> Barry if you can chime in here that would be great, thanks everyone.
> 
> TK
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