I2C-CPEV National Semiconductor, I2C-CPEV Datasheet - Page 19

• Manufacturer Part Number: I2C-CPEV
• Description: BOARD INTERFACE USB I2C
• Manufacturer: National Semiconductor

Specifications of I2C-CPEV

• Main Purpose: Interface, USB to I²C
• Utilized Ic / Part: COP8CBE9
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Secondary Attributes: -
• Embedded: -
• Primary Attributes: -

9.0 Pin Descriptions
of G0 - G3 and RESET. For proper operation, no connection
should be made on the device side of the emulator connec-
tor.
10.0 Functional Description
The architecture of the device is a modified Harvard archi-
tecture. With the Harvard architecture, the program memory
(Flash) is separate from the data store memory (RAM). Both
Program Memory and Data Memory have their own separate
addressing space with separate address buses. The archi-
tecture, though based on the Harvard architecture, permits
transfer of data from Flash Memory to RAM.
10.1 CPU REGISTERS
The CPU can do an 8-bit addition, subtraction, logical or shift
operation in one instruction (t
There are six CPU registers:
10.3 DATA MEMORY
The data memory address space includes the on-chip RAM
and data registers, the I/O registers (Configuration, Data and
Pin), the control registers, the MICROWIRE/PLUS SIO shift
register, and the various registers, and counters associated
with the timers and the USART (with the exception of the
IDLE timer). Data memory is addressed directly by the in-
struction or indirectly by the B, X and SP pointers.
The data memory consists of 256 bytes of RAM. Sixteen
bytes of RAM are mapped as “registers” at addresses 0F0 to
0FF Hex. These registers can be loaded immediately, and
COP8CBE9
COP8CCE9
Device
FIGURE 6. Emulation Connection
Size (Flash)
Program
Memory
8192
C
) cycle time.
(Continued)
Flash Memory
TABLE 1. Available Memory Address Ranges
Page Size
(Bytes)
64
20022509
Option Register
Address (Hex)
1FFF
19
A is the 8-bit Accumulator Register
PC is the 15-bit Program Counter Register
B is an 8-bit RAM address pointer, which can be optionally
post auto incremented or decremented.
X is an 8-bit alternate RAM address pointer, which can be
optionally post auto incremented or decremented.
S is the 8-bit Data Segment Address Register used to extend
the lower half of the address range (00 to 7F) into 256 data
segments of 128 bytes each.
SP is the 8-bit stack pointer, which points to the subroutine/
interrupt stack (in RAM). With reset the SP is initialized to
RAM address 06F Hex. The SP is decremented as items are
pushed onto the stack. SP points to the next available loca-
tion on the stack.
All the CPU registers are memory mapped with the excep-
tion of the Accumulator (A) and the Program Counter (PC).
10.2 PROGRAM MEMORY
The program memory consists of 8192 bytes of Flash
Memory. These bytes may hold program instructions or con-
stant data (data tables for the LAID instruction, jump vectors
for the JID instruction, and interrupt vectors for the VIS
instruction). The program memory is addressed by the 15-bit
program counter (PC). All interrupts in the device vector to
program memory location 00FF Hex. The program memory
reads 00 Hex in the erased state. Program execution starts
at location 0 after RESET.
If a Return instruction is executed when the SP contains 6F
(hex), instruction execution will continue from Program
Memory location 7FFF (hex). If location 7FFF is accessed by
an instruction fetch, the Flash Memory will return a value of
00. This is the opcode for the INTR instruction and will cause
a Software Trap.
For the purpose of erasing and rewriting the Flash Memory,
it is organized in pages of 64 bytes as show in Table 1.
also decremented and tested with the DRSZ (decrement
register and skip if zero) instruction. The memory pointer
registers X, SP, B and S are memory mapped into this space
at address locations 0FC to 0FF Hex respectively, with the
other registers being available for general usage.
The instruction set permits any bit in memory to be set, reset
or tested. All I/O and registers (except A and PC) are
memory mapped; therefore, I/O bits and register bits can be
directly and individually set, reset and tested. The accumu-
lator (A) bits can also be directly and individually tested.
Note: RAM contents are undefined upon power-up.
PU is the upper 7 bits of the program counter (PC)
PL is the lower 8 bits of the program counter (PC)
Data Memory
Size (RAM)
256
Segments
Available
0-1
Maximum
Address
(HEX)
www.national.com
RAM
017F