RFPIC12C509AG Datasheet, PDF (11/104 Pages) Microchip Technology – 18/20-Pin 8-Bit CMOS Microcontroller with UHF ASK/FSK Transmitter

rfPIC12C509AG/509AF
3.0 ARCHITECTURAL OVERVIEW
The rfPIC12C509AG/509AF is a low-cost, high perfor-
mance, 8-bit, fully static, EPROM-based CMOS micro-
controller combined with a UHF ASK/FSK transmitter.
There are no internal electrical connections between
the PICmicro MCU and the transmitter.
Section 7 has a detailed description of UHF ASK/FSK
transmitter.
3.1 PICmicro Microcontroller Unit
The high performance of the rfPIC12C509AG/509AF
family can be attributed to a number of architectural
features commonly found in RISC microprocessors. To
begin with, the rfPIC12C509AG/509AF uses a Harvard
architecture in which program and data are accessed
on separate buses. This improves bandwidth over tra-
ditional von Neumann architecture where program and
data are fetched on the same bus. Separating program
and data memory further allows instructions to be sized
differently than the 8-bit wide data word. Instruction
opcodes are 12 bits wide making it possible to have all
single word instructions. A 12-bit wide program mem-
ory access bus fetches a 12-bit instruction in a single
cycle. A two-stage pipeline overlaps fetch and execu-
tion of instructions. Consequently, all instructions (33)
execute in a single cycle (1µs @ 4MHz) except for pro-
gram branches.
The table below lists program memory (EPROM) and
data memory (RAM) for each device.
Memory
Device
EPROM RAM
Program Data
rfPIC12C509AG 1024 x 12 41
rfPIC12C509AF 1024 x 12 41
Transmitter
ASK
ASK/FSK
The rfPIC12C509AG/509AF can directly or indirectly
address its register files and data memory. All special
function registers including the program counter are
mapped in the data memory. The rfPIC12C509AG/
509AF has a highly orthogonal (symmetrical) instruc-
tion set that makes it possible to carry out any opera-
tion on any register using any addressing mode. This
symmetrical nature and lack of special optimal situa-
tions make programming with the rfPIC12C509AG/
509AF simple yet efficient. In addition, the learning
curve is reduced significantly.
The rfPIC12C509AG/509AF contains an 8-bit ALU and
working register. The ALU is a general purpose arith-
metic unit. It performs arithmetic and Boolean functions
between data in the working register and any register
file.
The ALU is 8 bits wide and capable of addition, subtrac-
tion, shift and logical operations. Unless otherwise
mentioned, arithmetic operations are two's comple-
ment in nature. In two-operand instructions, typically
one operand is the W (working) register. The other
operand is either a file register or an immediate con-
stant. In single operand instructions, the operand is
either the W register or a file register.
The W register is an 8-bit working register used for ALU
operations. It is not an addressable register.
Depending on the instruction executed, the ALU may
affect the values of the Carry (C), Digit Carry (DC), and
Zero (Z) bits in the STATUS register. The C and DC bits
operate as a borrow and digit borrow out bit, respec-
tively, in subtraction. See the SUBWF and ADDWF
instructions for examples.
3.2 UHF ASK/FSK Transmitter
The Transmitter is a fully integrated UHF ASK/FSK
transmitter consisting of crystal oscillator, phase-
locked loop (PLL), open-collector differential-output
Power Amplifier (PA), and mode control logic. External
components consist of bypass capacitors, crystal, and
PLL loop filter. There are no internal electrical connec-
tions between the PICmicro MCU and the transmitter.
The rfPIC12C509AG is capable of Amplitude Shift Key-
ing (ASK) modulation by turning the PA on and off. The
rfPIC12C509AF is capable of ASK or Frequency Shift
Keying (FSK) modulation by employing an internal FSK
switch to pull the transmitter crystal via a second load
capacitor.
The PICmicro MCU oscillator is independent from the
transmitter crystal oscillator. The transmit frequency is
fixed and set by an external reference crystal. Trans-
mit frequencies in the range of 310 to 480 MHz can be
selected. Output drive is an open-collector differential
amplifier. The differential output is well suited for loop
antennas. Output power is adjustable from +2 dBm to
-12 dBm in six discrete steps.
The rfPIC12C509AG/509AF are radio frequency (RF)
emitting devices. Wireless RF devices are governed by
a country’s regulating agency. For example, in the
United States it is the Federal Communications Com-
mittee (FCC) and in Europe it is the European Confer-
ence of Postal and Telecommunications
Administrations (CEPT). It is the responsibility of the
designer to ensure that their end product conforms to
rules and regulations of the country of use and/or sale.
© 2001 Microchip Technology Inc.
Preliminary
DS70031A-page 9