th7120 ETC-unknow, th7120 Datasheet - Page 10

• Manufacturer Part Number: th7120
• Description: 930mhz Fsk/fm/ask Transceiver
• Manufacturer: ETC-unknow

Programmable Channel Operation
Serial Control Interface Description
A 3-wire (SCLK, SDTA, SDEN) Serial Control Interface (SCI) is used to program the transceiver in multi-
channel mode (see Fig. 2). At each rising edge of the SCLK signal, the logic value on the SDTA pin is written
into a 24-bit shift register. The data stored in the shift register are loaded into one of the 4 appropriate latches
on the rising edge of SDEN. The control words are 24 bits lengths: 2 address bits and 22 data bits. The first
two bits (bit 23 and 22) are latch address bits. As additional leading bits are ignored, only the least significant
24 bits are serial-clocked into the shift register. The first incoming bit is the most significant bit (MSB). To
program the transceiver in multi-channel application, four 24-bit words may be sent: A-word, B-word, C-word
and D-word. If individual bits within a word have to be changed, then it is sufficient to program only the appro-
priate 24-bit word. The serial data input timing and the structure of the control words are illustrated in Fig. 2
and 3. Table REGISTER SETTINGS describes the function of each bit.
Due to the static CMOS design, the SCI consumes virtually no current and it can be programmed in active as
well as in standby mode.
3901007120
Rev. 005
SDTA
SCLK
SDEN
Figure 2: SCI block diagram
Figure 3: Serial data input timing
SDTA
SCLK
SDEN
Invalid
data
t
CS
bit 23
MSB
ADDR DECODER
SHIFT REGISTER
24-BIT
2
bit 22
t
CH
‘
‘
‘
‘ ’
00
01
10
11
22
’
’
’
Page 10 of 28
t
CWL
bit 1
t
22
22
22
22
CWH
B - LATCH
C - LATCH
D - LATCH
FSK/FM/ASK Transceiver
A - LATCH
bit 0
LSB
t
ES
Invalid
data
t
EW
300 to 930MHz
22
22
22
22
TH7120
t
EH
Data Sheet
Jan. 2002
A-word
B-word
C-word
D-word