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9. 3-wire Serial Configuration Interface
CC1000
is configured via a simple 3-wire
interface (PDATA, PCLK and PALE).
There are 28 8-bit configuration registers,
each addressed by a 7-bit address. A
Read/Write bit initiates a read or write
operation. A full configuration of
requires sending 22 data frames of 16 bits
each (7 address bits, R/W bit and 8 data
bits).
The
time
needed
configuration
depend
frequency. With a PCLK frequency of 10
MHz the full configuration is done in less
than 46 µs. Setting the device in power
down mode requires sending one frame
only and will in this case take less than 2
µs. All registers are also readable.
In each write-cycle 16 bits are sent on the
PDATA-line. The seven most significant
bits of each data frame (A6:0) are the
address-bits. A6 is the MSB (Most
Significant Bit) of the address and is sent
as the first bit. The next bit is the R/W bit
(high for write, low for read). During
address and R/W bit transfer the PALE
(Program Address Latch Enable) must be
kept low. The 8 data-bits are then
transferred (D7:0). See Figure 4.
T
SA
PCLK
PDATA
6
PALE
Figure 4. Configuration registers write operation
CC1000
for
a
full
on
the
PCLK
T
T
CH,min
CL,min
Address
Write mode
5
4
3
2
1
0
SWRS048A
The timing for the programming is also
shown in Figure 4 with reference to Table
2. The clocking of the data on PDATA is
done on the negative edge of PCLK.
When the last bit, D0, of the 8 data-bits
has been loaded, the data word is loaded
in the internal configuration register.
The configuration data is stored in internal
RAM. The data is retained during power-
down mode, but not when the power-
supply is turned off. The registers can be
programmed in any order.
The configuration registers can also be
read by the microcontroller via the same
configuration interface. The seven address
bits are sent first, then the R/W bit set low
to initiate the data read-back.
returns the data from the addressed
register. PDATA is in this case used as an
output and must be tri-stated (or set high n
the case of an open collector pin) by the
microcontroller during the data read-back
(D7:0). The read operation is illustrated in
Figure 5.
T
HA
T
T
SA
HD
W
7
6
5
CC1000
CC1000
then
T
SD
Data byte
4
3
2
1
0
Page 13 of 55
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