PNP-2850-L22 Universal Microwave Corporation, PNP-2850-L22 Datasheet - Page 4

• Manufacturer Part Number: PNP-2850-L22
• Description: Intelligent Frequency Synthesizers
• Manufacturer: Universal Microwave Corporation

Digital Interface
Overview
The PNP family of intelligent Frequency Synthesizers can
be controlled through the use of a microprocessor inter-
face or Bus. Several protocols are supported by PNP
devices, although this specification will focus on SPI Bus,
MICROWIRE-Interface and I
For SPI and MICROWIRE applications, PNP devices re-
quire a single 32 bit string of serial data to set frequency
or to change its internal settings (Figure 1). I
izes some unique control bits and requires the addition of
an ADDRESS byte, increasing the serial bit-stream for
this protocol to 47 bits per command (Figure 2).
The PNP device is programmed at the factory with pre-
sets for the START, STOP, STEP and REFERENCE
registers. It is not necessary to re-load any of these reg-
isters if the factory values are acceptable. If the applica-
tion requires different values than the factory pre-sets,
then the PNP device must first be initialized by loading
data into each of the affected registers. It is not neces-
sary to re-load any registers that are already set properly
for the application. START defines the lowest desired
frequency of operation. STOP defines the highest de-
sired frequency of operation. STEP is used to channelize
the band and REFERENCE defines the frequency of the
external reference. Once the PNP device is initialized, a
fixed number channels are available. Loading the CHAN-
NEL register sets the operating frequency of the PNP
device. The formula for calculating the operating fre-
quency is:
MICROWIRE Interface and SPI Bus
MICROWIRE-Interface and SPI Bus are extremely similar
protocols (Figures 6 & 7).
the PNP device on the rising edge of the CLOCK input.
CS, or chip select not, must be in a low state for the in-
coming DATA bits to be accepted. After all 32 bits have
been clocked in, the CS line must transition high for the
DATA string to be latched. After the string is latched, the
information in the FUNCTION block (Figure 5) deter-
mines where the data will be routed internally.
I
The I
over a two wire interface. PNP modules are configured
as “slaves” or receive-only devices and can only listen for
commands from the “master” which is typically a micro-
processor. The I
data) and SCL (serial clock) lines. In order to use the I
START(Hz) + (CHANNEL * STEP(Hz)) = Frequency(Hz)
2
C Bus
2
C Bus is a high-speed method of communicating
2
C two wire Bus consists of SDA (serial
DATA bits are clocked into
2
C Bus implementations.
2
C Bus util-
2
C
Bus for control of the PNP synthesizer module, the DA2
line (see Package Drawing, Page 1) must be tied to Digi-
tal Ground. Additionally, the SDA and SCL lines must be
pulled up to D
Multiple PNP devices can reside on the same two wire
Bus without the danger of corrupted data or data colli-
sions. Device selection is accomplished by sending a
slave address preceding each string of data. If only one
PNP device will be used on the I
pre-set base address will operate properly. If more than
one PNP device will reside on the same I
modules with unique address locations must be used.
This should be specified when ordering (see Ordering
Guide on page 3). For additional information refer to the
I
I
Transferring data to PNP synthesizers using I
varies significantly from that of SPI or MICROWIRE.
PNP modules operate as slaves on the I
not write to the Bus. However, due to the fact that many
devices might reside on the same Bus, addressing must
be used to direct the flow of data traffic. So, within the bit
stream sent to the PNP device, there is a block of data
that comprises the ADDRESS byte. Within this address
byte there are 7 bits that are used for the address loca-
tion and the eighth is used as a read/write (R/W) bit.
Since PNPs are slaves and will never write to the I
Bus, this bit will always be set to 0 (logic low).
Each data string is sent using a series of five single byte
blocks. I
gin with a master generated START (S). Each byte
within the string must end with a slave generated AC-
KNOWLEDGE (A). Finally, after all five bytes are gener-
ated, the transfer is concluded with a master generated
STOP (P). The master generated STOP must be exe-
cuted following each data string for the values to be ac-
cepted by the PNP device. If this condition is not satis-
fied and a new master generated START occurs, the
PNP device will purge the previous data without updating
the desired attribute. REPEATED START (S
is not allowed when sending data to the PNP device.
The flow of data bytes to the PNP device is outlined in
Figure 2. Since FUNCTION SELECT and MULTIPLIER
are 4 bits each, these blocks of data are combined into
one byte. Additionally, since the FREQUENCY/
CHANNEL block of data is 24 bits long, it must be frag-
mented into three individual bytes as shown.
2
2
C Bus specification (copyright Philips Corp).
C Implementation
2
C protocol requires that each string of data be-
vdd
using external resistors.
PNP-2850-L22
2
C Bus, then the factory
2
2
C Bus and do
C Bus, then
r
2
) operation
C protocol
2
C