Radiometrix Ltd

Control44

page 3

Pin

Name

Input/Output

Description

1

STB

Output

Positive going pulse on reception of valid data packet. 10µs 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

10-13

DA3:DA0

Output

14

Vdd

Supply

4.5-5.5V supply (decouple with 0.1µF close to IC)

15

OSC2

Output

16

OSC1

Input

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. 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

0

0

10

0

11

1ms

500

µs

1

Figure 4: 1kbps differential Manchester coding of ‘1’ and ‘0’