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Hi...

I'm disassembling some code in a device i don't have physical
access to... and the program (which does work) is appearing to
use all eight pins of Port A as both outputs and inputs (without
flipping a data direction bit, either).

Other members of this product family use an MC68HC11E1CFN2,
and those devices do not attempt use the 0,1,2 Port A bits
as output, they're solely used for input (as the Freescale
reference manual specifies, and backs up with the internal
gate-diagram).

The product run of the puzzling device is roughly 10,000,
so i'd be surprised if they had ordered a custom masking.

My questions are: is there a Freescale, or 2nd sourced,
version of the 68hc11 with eight bidirectional Port A pins?
(for that matter, who does second-source the 68hc11?)

I'm pretty sure that the product -does- use a 68hc11,
since they use an Analog channel, the serial RxD and TxD,
and the rest of their device register usage matches 68hc11
practice (as demonstrated in the rest of the product family).

The product in question is a Meade RCX400 telescope, with
an Autostar II controller. They're using Port A as high-order
memory address lines to access 4 megs of FlashRam.

The device registers have been mapped down to 0000-003F,
which leads to the 3rd question of: if it's accessing the
device registers, do the external data and address lines
show what's going on? Could external circuity be latching
what was "output" to 0000, and then just drive the Port A
pins to provide the input functionality?

The known-to-be-MC68HC11E1CFN2 other products are their LX200GPS
with its Autostar II (which shares a 90%-common codebase with the
RCX400), and their 497 Autostar, used on ETX90, LXD55/75 and LX90
scopes. In those models they distribute the memory addressing
duties across the defined-as-output pins of Port A plus a
few pins in Port D.

thanks
--dick


(You need to be a member of m68hc11 -- send a blank email to m68hc11-subscribe@yahoogroups.com )

Without checking the whole range of HC11's - I see:

2 i/o's
3 x input only
3 x output only

PA0-2 Input only
PA3 Input/Output
PA4-6 Output only
PA7 Input/Output.

Is that changeable on a mask? I wouldn't have thought so.

TJ

----- Original Message -----
From: autostaretx
To: m...@yahoogroups.com
Sent: Saturday, July 28, 2007 6:07 PM
Subject: [m68HC11] Port A ...all pins as outputs?
Hi...

I'm disassembling some code in a device i don't have physical
access to... and the program (which does work) is appearing to
use all eight pins of Port A as both outputs and inputs (without
flipping a data direction bit, either).

Other members of this product family use an MC68HC11E1CFN2,
and those devices do not attempt use the 0,1,2 Port A bits
as output, they're solely used for input (as the Freescale
reference manual specifies, and backs up with the internal
gate-diagram).

The product run of the puzzling device is roughly 10,000,
so i'd be surprised if they had ordered a custom masking.

My questions are: is there a Freescale, or 2nd sourced,
version of the 68hc11 with eight bidirectional Port A pins?
(for that matter, who does second-source the 68hc11?)

I'm pretty sure that the product -does- use a 68hc11,
since they use an Analog channel, the serial RxD and TxD,
and the rest of their device register usage matches 68hc11
practice (as demonstrated in the rest of the product family).

The product in question is a Meade RCX400 telescope, with
an Autostar II controller. They're using Port A as high-order
memory address lines to access 4 megs of FlashRam.

The device registers have been mapped down to 0000-003F,
which leads to the 3rd question of: if it's accessing the
device registers, do the external data and address lines
show what's going on? Could external circuity be latching
what was "output" to 0000, and then just drive the Port A
pins to provide the input functionality?

The known-to-be-MC68HC11E1CFN2 other products are their LX200GPS
with its Autostar II (which shares a 90%-common codebase with the
RCX400), and their 497 Autostar, used on ETX90, LXD55/75 and LX90
scopes. In those models they distribute the memory addressing
duties across the defined-as-output pins of Port A plus a
few pins in Port D.

thanks
--dick

[Non-text portions of this message have been removed]


(You need to be a member of m68hc11 -- send a blank email to m68hc11-subscribe@yahoogroups.com )

> -----Original Message-----
> From: m...@yahoogroups.com
> [mailto:m...@yahoogroups.com] On Behalf Of autostaretx
> Sent: Saturday, July 28, 2007 7:07 PM
> To: m...@yahoogroups.com
> Subject: [m68HC11] Port A ...all pins as outputs?
>
> Hi...
>
> I'm disassembling some code in a device i don't have physical
> access to... and the program (which does work) is appearing to
> use all eight pins of Port A as both outputs and inputs (without
> flipping a data direction bit, either).

Maybe the program is just reading back the status of the output only pins
(that is, not reading any input data but just using the output register as a
memory location for storing the status that was set earlier)?

Regards,
Anders



(You need to be a member of m68hc11 -- send a blank email to m68hc11-subscribe@yahoogroups.com )

--- In m...@yahoogroups.com, "Anders Friberg"
wrote:
> > -----Original Message-----
> > From: m...@yahoogroups.com
> > [mailto:m...@yahoogroups.com] On Behalf Of autostaretx
> > Sent: Saturday, July 28, 2007 7:07 PM
> > To: m...@yahoogroups.com
> > Subject: [m68HC11] Port A ...all pins as outputs?
> >
> > Hi...
> >
> > I'm disassembling some code in a device i don't have physical
> > access to... and the program (which does work) is appearing to
> > use all eight pins of Port A as both outputs and inputs (without
> > flipping a data direction bit, either).
>
> Maybe the program is just reading back the status of the output
> only pins (that is, not reading any input data but just using
> the output register as a memory location for storing the status
> that was set earlier)?

The external device that is being controlled by the outputs is
functioning... so they're not just using it as a holding register.
In one routine they're even reading L0000 into A, incrementing
the register, and then sending it back out.

The bits are being used as address lines ... the high bits
select one-of-eight FlashRam chips, and the lower bits serve
as 32KB "page" selectors.

thanks
--dick


(You need to be a member of m68hc11 -- send a blank email to m68hc11-subscribe@yahoogroups.com )

> -----Original Message-----
> From: m...@yahoogroups.com
> [mailto:m...@yahoogroups.com] On Behalf Of autostaretx
> Sent: Sunday, July 29, 2007 2:48 AM
> To: m...@yahoogroups.com
> Subject: [m68HC11] Re: Port A ...all pins as outputs?
>
> --- In m...@yahoogroups.com, "Anders Friberg"
> wrote:
> >
> >
> > > -----Original Message-----
> > > From: m...@yahoogroups.com
> > > [mailto:m...@yahoogroups.com] On Behalf Of autostaretx
> > > Sent: Saturday, July 28, 2007 7:07 PM
> > > To: m...@yahoogroups.com
> > > Subject: [m68HC11] Port A ...all pins as outputs?
> > >
> > > Hi...
> > >
> > > I'm disassembling some code in a device i don't have physical
> > > access to... and the program (which does work) is appearing to
> > > use all eight pins of Port A as both outputs and inputs (without
> > > flipping a data direction bit, either).
> >
> > Maybe the program is just reading back the status of the output
> > only pins (that is, not reading any input data but just using
> > the output register as a memory location for storing the status
> > that was set earlier)?
>
> The external device that is being controlled by the outputs is
> functioning... so they're not just using it as a holding register.
> In one routine they're even reading L0000 into A, incrementing
> the register, and then sending it back out.
>
> The bits are being used as address lines ... the high bits
> select one-of-eight FlashRam chips, and the lower bits serve
> as 32KB "page" selectors.
>

Did you check the old Hitachi Motorola compatible 8-bit family?

I have no doc available just now but there were type nr as 6303, 68301 etc,
some were in 40-pin DIP and some in 64-pin shrink DIP with many ports. They
were often "enhanced" and maybe their Port A was designed like that?

Regards,
Anders


(You need to be a member of m68hc11 -- send a blank email to m68hc11-subscribe@yahoogroups.com )

Someone opened their telescope up and -looked-.

The chip in the RCX400 telescope is Freescale's MC68HC11F1CFN4

That chip -does- have a fully bidirectional Port A,
which solves the mystery i was seeing.

The F1 comes in a 68 pin package with fully non-multiplexed
address and data bus pins (it's not available as a 52-pin,
unlike the E1).

To read Motorola's/Freescale chip-history, it's a 73% die
reduction of the E9, and has "chip select" features which
allow address-range-selected memory clock-stretch control
for banks of slower external memory.

The F1 is given a short description in the 68hc11 reference manual,
but they did not bother to mention the Port A difference.

thanks to all who gave thought to this...
have fun
--dick


(You need to be a member of m68hc11 -- send a blank email to m68hc11-subscribe@yahoogroups.com )

Live and learn.
----- Original Message -----
From: autostaretx
To: m...@yahoogroups.com
Sent: Sunday, July 29, 2007 6:38 PM
Subject: [m68HC11] Re: Port A ...all pins as outputs?
Someone opened their telescope up and -looked-.

The chip in the RCX400 telescope is Freescale's MC68HC11F1CFN4

That chip -does- have a fully bidirectional Port A,
which solves the mystery i was seeing.

The F1 comes in a 68 pin package with fully non-multiplexed
address and data bus pins (it's not available as a 52-pin,
unlike the E1).

To read Motorola's/Freescale chip-history, it's a 73% die
reduction of the E9, and has "chip select" features which
allow address-range-selected memory clock-stretch control
for banks of slower external memory.

The F1 is given a short description in the 68hc11 reference manual,
but they did not bother to mention the Port A difference.

thanks to all who gave thought to this...
have fun
--dick

[Non-text portions of this message have been removed]


(You need to be a member of m68hc11 -- send a blank email to m68hc11-subscribe@yahoogroups.com )