Fluke 2625A User Manual
Theory of Operation (2635A)
Detailed Circuit Description
2A
2A-39
The Memory Card Controller provides a register based interface for the Microprocessor
to use to access data stored on industry standard PCMCIA memory cards. A 26 bit
counter controls the address bus (CA<0> through CA<25>) to the PCMCIA Memory
Card Connector (A6P1). An eight bit data bus(CD<0> through CD<7>) and memory
card control signals (REG*, CE1*, CRD*, and CWR*) control accesses to memory on
the card.
to use to access data stored on industry standard PCMCIA memory cards. A 26 bit
counter controls the address bus (CA<0> through CA<25>) to the PCMCIA Memory
Card Connector (A6P1). An eight bit data bus(CD<0> through CD<7>) and memory
card control signals (REG*, CE1*, CRD*, and CWR*) control accesses to memory on
the card.
The REG* signal (A6U1-8) is like an additional address bit. When REG* is slow
(A6U1-8), read and write accesses go to "attribute" memory on the card. Attribute
memory is typically a small EEPROM on the memory card that contains special
information that specifies the manufacturer of the card, type and size of memory on the
card, memory speed, etc. When REG* is high, read and write accesses go to the
"common" memory on the card. Common memory is the Static RAM on the memory
cards used in this instrument.
(A6U1-8), read and write accesses go to "attribute" memory on the card. Attribute
memory is typically a small EEPROM on the memory card that contains special
information that specifies the manufacturer of the card, type and size of memory on the
card, memory speed, etc. When REG* is high, read and write accesses go to the
"common" memory on the card. Common memory is the Static RAM on the memory
cards used in this instrument.
Typically, information is read and written to the memory card in a sequential manner
where the address counter automatically increments after the end of each read or write
cycle. When the Memory Card Controller reads data from the memory card data bus
(CD<0> through CD<7>), CE1* (A6U1-62) goes low followed by CRD* (A6U1-63)
going low. The data from the memory card then goes through the Memory Card
controller and is read by the Microprocessor on the D8 through D15 data bus lines.Data
is written to the memory card in a similar manner, except that the data goes from the
Microprocessor through the memory Card Controller and to the Memory Card with
CWR* (A6U2-64) going low to enable the writing of the data to the memory. The
purpose of A6U2 and resistors A6R2, A6R5, and A6R7 is to ensure that data on the
Memory Card is not accidentally modified during the time that the instrument is being
powered up or down. Each of the Memory Card data bus lines (CD<0> through CD<7>)
has a series resistor (A6Z2) that helps ensure that the instrument meets EMI/EMC
performance requirements.
where the address counter automatically increments after the end of each read or write
cycle. When the Memory Card Controller reads data from the memory card data bus
(CD<0> through CD<7>), CE1* (A6U1-62) goes low followed by CRD* (A6U1-63)
going low. The data from the memory card then goes through the Memory Card
controller and is read by the Microprocessor on the D8 through D15 data bus lines.Data
is written to the memory card in a similar manner, except that the data goes from the
Microprocessor through the memory Card Controller and to the Memory Card with
CWR* (A6U2-64) going low to enable the writing of the data to the memory. The
purpose of A6U2 and resistors A6R2, A6R5, and A6R7 is to ensure that data on the
Memory Card is not accidentally modified during the time that the instrument is being
powered up or down. Each of the Memory Card data bus lines (CD<0> through CD<7>)
has a series resistor (A6Z2) that helps ensure that the instrument meets EMI/EMC
performance requirements.
The Memory Card Controller detects the insertion and removal of a Memory Card and
interrupts the microprocessor by driving the MCINT* signal(A6U1-60) low. When a
Memory Card is inserted in the PCMCIA Memory Card Connector, the CD1 (A6U1-19)
and CD2 (A6U1-21) inputs on the Memory Card Controller are driven to 0V dc and
Microprocessor (A1U1) is interrupted. The Microprocessor then powers up the Memory
Card by setting A6U1-26 low, which turns on FET A6Q1 by driving the gate low
through resistor A6R13. When FET A6Q1 is turned on the Memory Card power (CVCC
and CVPP) is approximately +5.0V dc. When the Microprocessor has completed a data
transfer with the Memory Card, FET A6Q1 is turned off again by driving A6U1-26 high.
interrupts the microprocessor by driving the MCINT* signal(A6U1-60) low. When a
Memory Card is inserted in the PCMCIA Memory Card Connector, the CD1 (A6U1-19)
and CD2 (A6U1-21) inputs on the Memory Card Controller are driven to 0V dc and
Microprocessor (A1U1) is interrupted. The Microprocessor then powers up the Memory
Card by setting A6U1-26 low, which turns on FET A6Q1 by driving the gate low
through resistor A6R13. When FET A6Q1 is turned on the Memory Card power (CVCC
and CVPP) is approximately +5.0V dc. When the Microprocessor has completed a data
transfer with the Memory Card, FET A6Q1 is turned off again by driving A6U1-26 high.
When a Memory Card is inserted and powered up, the Memory Card outputs some status
signals to the Memory Card Controller. If the Memory Card write protect switch is
protecting data on the card, the WP signal (A6U1-22) is high. The status of the Memory
Card battery is output on the BVD1 (A6P1-18) and BVD2 (A6P1-20) pins of the
Memory Card Connector. If either of these battery status signals is low when the
Memory Card is powered up, then the Microprocessor will turn on LED A6DS2 by
driving A6U1-24 low. The Busy status LED (A6DS1) is turned on by driving A6U1-25
low when the Microprocessor has powered up the Memory Card and is transferring data
to or from the card.
signals to the Memory Card Controller. If the Memory Card write protect switch is
protecting data on the card, the WP signal (A6U1-22) is high. The status of the Memory
Card battery is output on the BVD1 (A6P1-18) and BVD2 (A6P1-20) pins of the
Memory Card Connector. If either of these battery status signals is low when the
Memory Card is powered up, then the Microprocessor will turn on LED A6DS2 by
driving A6U1-24 low. The Busy status LED (A6DS1) is turned on by driving A6U1-25
low when the Microprocessor has powered up the Memory Card and is transferring data
to or from the card.
2A-74. PCMCIA Memory Card Connector
The PCMCIA Memory Card Connector (A6P1) is a 68 pin connector that meets the
requirements of the Personal Computer Memory Card International Association. This
connector has pins that are three different lengths: the card detection pins (CD1 and
CD2) are the shortest, the power and ground pins are the longest, and the rest of the pins
are a length in between. This ensures that on memory card insertion, the power and
requirements of the Personal Computer Memory Card International Association. This
connector has pins that are three different lengths: the card detection pins (CD1 and
CD2) are the shortest, the power and ground pins are the longest, and the rest of the pins
are a length in between. This ensures that on memory card insertion, the power and