Radiometrix Ltd

CTA88

page 5

Incompatibilities: Certain operating modes are not compatible with some of the others:

RX 101 (toggle) doesn't work with TX 101 (periodic send) as the outputs switch on and off at the send

rate

RX 100 (set and reset) doesn't work with TX 101 (as the response is sluggish) and doesn't need TX

010 (constant)

RX 101 (toggle) is also not best suited to extreme range operation, where the initiation can be a little

sporadic.

(At extreme range, latched (011) or set/reset (100) are the best receiver modes, combined with TX 100

(send on any '1') as in this mode the failure of any single burst to be received matters less, as the

operator can continue to operate the transmitter until the receiver actuates )

Serial operation: The CTA88 is capable of a very simple, single byte, serial link operation. It is

selected by a '110' mode input.

This function is mainly intended for diagnostic work in the lab, but it does allow a pc to send or receive

CTA88 command bursts. Address is still selected by the parallel inputs

On the RX:

D4 = 'true' RS232 output

(+ve = low (0), 0V = idle/mark state)

D5 = 'inverted' RS232 output (+ve = idle/'mark' (1) state)

D6 : high for 500uS before, and during, serial byte output

On the TX

D4 = RS232 input

D5 : low = set 'true' input polarity, high = set 'inverted' input polarity

In all cases a single 9600 baud byte is received or sent.

The link is not transparent: on the TX end the 'tx on' pin can be used as a 'busy' output

Timeout: In modes 001 and 010, the receiver outputs the last received data for a given period, before

resetting D0-D7.

Any subsequent transmission will over-ride the current output state and reset the timer, even if the

timeout period has not expired.

The short period is set to be slightly longer than the time between consecutive transmit bursts in a

continuous mode.

The long timeout is usable with the randomised periodic transmission mode (101), as the 3 second

timeout is longer than the longest delay between transmissions in this mode.

Versions of the chip can be supplied with this period extended to suit customer requirements

Ordering Information:

CTA88-000-SS

Standard (

≤4MHz)- No Frequency - Shrink Small Outline (SSOP)

CTA88-000-SO

Standard (

≤4MHz)- No Frequency - Small Outline (SO)

CTA88-000-DIL

Standard (

≤4MHz)- No Frequency - Plastic Dual In Package (PDIP)

CTA88L-000-SS

Low Voltage (

≤4MHz) - No Frequency - SSOP

CTA88L-000-SO

Low Voltage (

≤4MHz) - No Frequency - SO

CTA88L-000-DIL

Low Voltage (

≤4MHz) - No Frequency - PDIP

CTA88H-000-SS

High Speed (4MHz-20MHz) - No Frequency - SSOP

CTA88H-000-SO

High Speed (4MHz-20MHz) - No Frequency - SO

CTA88H-000-DIL

High Speed (4MHz-20MHz) - No Frequency - PDIP