M48A-000-DIL RADIOMETRIX, M48A-000-DIL Datasheet - Page 5

• Manufacturer Part Number: M48A-000-DIL
• Description: IC, CONTROLLER, SERIAL MODEM, 20DIP
• Manufacturer: RADIOMETRIX

Specifications of M48A-000-DIL

• Baud Rate: 4800baud
• Supply Voltage Range: 4.5V To 5.5V
• Operating Temperature Range: -40°C To +85°C
• Digital Ic Case Style: DIP
• No. Of Pins: 20
• Controller Type: MOSFET
• Data Format: Asynchronous

There is a 5 second timeout following the break within which the response must be sent , or the device
reverts to data mode. An ASCII 1 (ctrl A) resets the timeout and generates a new @ and random character
sequence.
[ 'Break' conditions can be generated in several ways. Some terminal emulators have alt or ctrl key
sequence. Dedicated hardware can be used to force a long (50-100mS) logic zero onto the TXD pin. Or an
ASCII zero can be sent at a much lower baud-rate ]
Once in setup mode, input bytes are stored in a 32 byte (maximum) command buffer and echoed back to the
serial output. Space characters are echoed back, but are not loaded into the buffer.
Commands are either short words or single command characters. (For example, a <cr> character is the
evaluate/process command). After successful execution of a command the device will reply with an 'OK'
message. Commands which program a value into the internal non-volatile E2PROM take around 50mS for
the write cycle,
The unit will only respond to certain command strings:
Upper case characters are used for all commands
Spaces are echoed, but are ignored by the parser
Single character command
General commands
Baud rate commands
As supplied, the main interface is set to 4800 baud, and the auxiliary port to 2400 baud .
Main port (b1) supports 1200, 2400, 4800, 9600, 19200, 38400, 57600, 76800
Aux port (b2) supports 1200, 2400, 4800, 9600 only
These setup parameters are immediately stored in E2PROM, and take effect right away. Remember that
baud rate scales with changes in crystal frequency (for example, if a 4.9152MHz crystal is fitted then BAUD
2400 will set a baud rate of 600).
When the interface baud rate is higher than the (4800 baud nominal) radio link interface speed, the system is
no longer truly transparent. As the modem is removing bytes from the buffer slower than the user interface is
supplying them, it is possible to over-fill the buffer and lose data, unless the user carefully controls the timing
Radiometrix Ltd
COMMANDS
Enter
Escape
?
/
-
&
delete
COMMANDS
DEFAULT
STATE
LOCK
EXIT
TEST
RX
COMMANDS
BAUD b1
BAUX b2
FUNCTION
The unit self-reprograms with ALL original factory preset values
Prints out the current operating parameters (a single minus sign, ascii 54, does the
same)
The unit now defaults to setup (rather than data) mode on power up
Return to data mode (same effect as an escape (ascii 27) byte)
If a LOCK command is in force, an escape byte has no effect, but EXIT overrides LOCK
Turns on the transmitter, and outputs a continuous 200Hz tone
This mode is disabled by any activity on the TXD input
Turn on the receiver/decoder (as if in data mode) and output received packets as
normal
This mode is disabled, and command mode re-entered, by any activity on the TXD input
FUNCTION
Set main port baud rate
set aux port baud rate
ASCII
13
27
63
47
54
38
127
FUNCTION
processes the input buffer contents (and clears the buffer)
terminates setup mode and returns to normal 'data' operation
prints the current contents of the command buffer
(as above)
shortcut for the STATE command (see later)
shortcut for the RX command
clears the input buffer
Only the first two digits are needed, i.e. BAUD 12 iss valid
NOTES
b1, b2 are baud rates
M48A Modem Data Sheet
page 5