Pin
1
2
Name
STB
Mode
Input/Output Description
Output
Input
Positive going pulse on reception of valid data packet. 10µs duration
RX=0V, TX=Vdd (no pull-up, only read at reset/power up)
3
4
5
NC
RST
VSS
A3:A0
DA3:DA0 Output
Vdd
OSC2
OSC1
Latch
Input
Supply
Input
Active Low Reset (Connect to user system reset or tie to Vdd)
Supply Ground
6-9
10-13
14
15
16
17
Least significant 4 bits of Address (Internal pull-ups to Vdd)1,5
Least significant 4 bits of Data A5
Supply
Output
Input
4.5-5.5V supply (decouple with 0.1µF close to IC)
3.58MHz resonator2
3.58MHz resonator2
Input
0V = latch DA3:D0 until next packet
Vdd = clear DA3:DA0 after 150ms (no pull-up)
Encoded Address and Data from RXD Output of RF Receiver
18
RXD
Input
Notes:
1. Only 4 of the 6 address bits are accessible. A5,A4 are set to 0 in CTR44
2. OSC1,2 require a 3.58MHz ceramic resonator with internal capacitors like Murata
CSTLA3M58G55-B0. If a 2 pin resonator or crystal is used, then two 15pF-22pF caps are
needed: one from OSC1 to 0V another from OSC2 to 0V. 100Ω series resistor between OSC2 and
crystal may be required when driving low frequency crystal with High Speed (H) CTR44H
version.
3. If a low going pulse of between 10µs and 50ms is applied to SEND pin then a single packet will
be transmitted
4. After asserting TXE low (active), the encoder allows 55ms for NBFM TX to power up and settle
5. Absolute maximum source/sink current from each DB3:DB0 pin is 25mA
6. TXE is an open drain output (no pull-up). Connect it to Vdd via a 10kΩ pull-up resistor
7. MODE pin is only read at reset/power up. Connect to either Vdd (Encoder) or 0V (Decoder).
8. Without external loads the CTR44 draws <2mA from 5V supply.
9. Standard version can be used down to 3V for <10MHz oscillator.
Low voltage version can be used down to 2V for <4MHz oscillator.
10. High Speed, CTR44H, version should not be used with Narrow Band FM radio modules.
Encoded Data Packet Format
Transmission format is 1kbps differential Manchester encoding when using 3.58MHz resonator.
Oscillator frequency can decreased to suit narrow band RF module data rate requirements. CTR44H IC
running at 20MHz can be used with wideband radio modules for fast data transmission.
0
1
0
1
1
0
0
0
1
1ms
500µs
Figure 4: 1kbps differential Manchester coding of ‘1’ and ‘0’
Radiometrix Ltd
Control44
page 3
RADIOMETRIX [ RADIOMETRIX LTD ]
