datasheet for CVM50XM by TechTools

datasheet for CVM50XM by TechTools
PO Box 462101
Garland, TX 75046-2101
Voice: (972) 272-9392 FAX: (972) 494-5814
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CVM50XM User’s Guide
The CVM50XM Member module emulates the PIC12C508 and PIC12C509 micro-controllers.
These devices are part of the 12 bit PICmicro family and therefore requires the 5X FAMILY
module (CVM5XF) for operation.
Due to BONDOUT limitations, the following features are either NOT SUPPORTED or are
modified slightly:
n The Wake-Up on pin change feature is not supported. The GPWU bit (OPTION.7) has no
affect. And the corresponding flag GPWUF (STATUS.7) has no meaning.
n The “weak pull-up” resistors are enabled/disabled by hardware jumpers on the member pod
rather than through the GPPU bit (OPTION.6). This bit has no affect.
n Mathias provides the operating clock so the OSCCAL register has no affect. You can
program Mathias for any clock frequency between 30KHz and 20MHz. The real PIC devices
run at around 4 MHz.
n GP3 is an INPUT ONLY on the real device to accommodate that pin’s alternative use as
MCLR. The emulator provides a full INPUT/OUTPUT pin for this function. The MCLR
signal is brought into the bondout chip through a different connection. You should ALWAYS
SET the corresponding TRIS bit for GP3 to properly emulate this INPUT-ONLY behavior.
n In an actual device, setting the TOCS bit (OPTION.5) automatically forces GP2 to be an
input, over-riding the TRIS bit for GP2. The emulator DOES NOT automatically force GP2
to be an input. YOU MUST SET TRIS.2 YOURSELF, if you use GP2 as a T0CS input.
n In an actual device, GPIO bits 6 and 7 are not implemented and will always read back ‘0’. In
the emulator, these bits are actually present and will read back whatever was last written to
them if the corresponding TRIS bits are cleared. If these TRIS bits are SET, then these bits
read FLOATING inputs and their value is indeterminate.
If the target permits, you can power the target from the emulator. To do so, place a jumper on JP1
between the center pin (+5EMU) and the pin marked +5VEXT. Moving the jumper the unmarked
position isolates the power rails. The default position is to ISOLATE the power rails.
JP2: Pin 5 function
functions as GP2.
functions as T0CKI
JP3*: Selects Pin 2 function
functions as GP5.
No connection.*
JP4*: Select Pin 3 function
functions as GP4.
No Connection*
* Since Mathias provides the clock for the bondout chip, JP3 and JP4 are usually set to the
GP position or removed completely. The no connection position is appropriate when your target
normally drives the OSC pins. This isolates the GP bits so that they are not in contention with
your target. NOTE: In either configuration, Mathias provides its own programmable clock,
making it easy to emulate a processor in either internal or external clock source mode.
JP5: Selects Pin 4 function
functions as GP2 with
the bondout MCLR
driven by Pin 4 with
tied to a weak pull to
a weak pullup to
Mathias VCC. (default)
Mathias VCC.
Functions as GP2 with
(the configuration to the left can cause
random resets if the target cable is not
attached to a target and JP1 is NOT
strapped to power the target. It is not
normally used.)
the bondout MCLR
tied to the TARGET
JP6,7 and 8: Weak Pull-ups
On the real devices, these three pull-ups are ALL ON or ALL OFF. To properly emulate this, you
should set ALL three jumpers to the ON position to enable the weak pull-ups. Conversely, you
should set ALL THREE jumpers to the OFF position to disable the weak pull-ups. These are set
to the ON position by default.
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