Radiometrix Ltd
Control44
page 3
Pin
Name
Input/Output
Description
1
STB
Output
Positive going pulse on reception of valid data packet. 10
µs duration
2
Mode
Input
RX=0V, TX=Vdd (no pull-up, only read at reset/power up)
3
NC
4
RST
Input
Active Low Reset (Connect to user system reset or tie to Vdd)
5
VSS
Supply
Supply Ground
6-9
A3:A0
Input
Least significant 4 bits of Address (Internal pull-ups to Vdd)1,5
10-13
DA3:DA0
Output
Least significant 4 bits of Data A5
14
Vdd
Supply
4.5-5.5V supply (decouple with 0.1
µF close to IC)
15
OSC2
Output
3.58MHz resonator2
16
OSC1
Input
3.58MHz resonator2
17
Latch
Input
0V = latch DA3:D0 until next packet
Vdd = clear DA3:DA0 after 150ms (no pull-up)
18
RXD
Input
Encoded Address and Data from RXD Output of RF Receiver
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. 100
Ω 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 10
µs 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 10k
Ω 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
0
0
10
0
11
1ms
500
µs
1
Figure 4: 1kbps differential Manchester coding of ‘1’ and ‘0’