RM024 – RAMP Wireless Module

Datasheet

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2.1.3

µP_RESET

µP_Reset provides a direct connection to the reset pin on the RM024 microprocessor and is used to force a hard

reset. For a valid reset, reset must be asserted Low for an absolute minimum of 250 nanoseconds (ns).

2.1.4

Command/Data

When logic High, the transceiver interprets incoming serial data as transmit data to be sent to other

transceivers. When logic Low, the transceiver interprets incoming serial data as command data. When logic Low,

data packets from the radio are not transmitted over the RF interface, however, incoming packets from other

radios are still received. Enabling CMD/Data RX Disable in the EEPROM causes incoming RF packets to be queued

by the receiving radio while CMD/Data is low. When CMD/Data goes high, the data is sent over the serial

interface.

2.1.5

In_Range

The In_Range pin is driven low when a client radio’s frequency hopping is synchronized with that of a server.

In_Range is always driven low on a server. Following boot, In_Range transitions low in approximately 12

milliseconds on a server. For a client, the In_Range takes an average of 500 milliseconds; this time is dependent

on the signal strength of the received beacon, the presence and strength of interference, and randomness of the

sync function. It can vary from 150 milliseconds to over 1500 milliseconds.

2.1.6 GO_0/Hop_Frame

The Hop Frame indicator functionality is disabled by default and controlled by the Control 1, Bit-6 EEPROM

setting. When enabled, this pin transitions logic Low at the start of a hop and transitions logic High at the

completion of a hop. The OEM host is not required to monitor hop frame.

2.1.7

RTS and Handshaking

With RTS mode disabled, the transceiver sends any received data to the OEM host as soon as it is received.

However, some OEM hosts are not able to accept data from the transceiver at all times. With RTS enabled in

EEPROM, the OEM host can prevent the transceiver from sending data by de-asserting RTS (High). Once RTS is

re-asserted (Low), the transceiver sends packets to the OEM host as they are received.

Note:

Leaving RTS de-asserted for too long can cause data loss once the transceiver’s transmit buffer

reaches capacity.

2.1.8

CTS Handshaking

If the transceiver buffer fills up and more bytes are sent to it before the buffer can be emptied, data loss occurs.

The transceiver prevents this loss by de-asserting CTS high as the buffer fills up and asserting CTS low as the

buffer is emptied. CTS should be monitored by the host device and data flow to the radio should be stopped

when CTS is high.

2.1.9 DE/RE

When enabled, RS485 Data Enable uses the DE/RE pin to control the DE pin on external RS-485 circuitry. When

the transceiver has data to send to the host, it asserts DE/RE High, sends the data to the host, and then takes

DE/RE low.