Specifications

Cinterion
®
BGS5 Hardware Interface Overview
2.1 Application Interface
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 BGS5_HID_v00.341 2013-09-23
Confidential / Preliminary
Page 14 of 41
2.1.3 Serial Interface ASC1
Four BGS5 GPIO lines can be configured as ASC1 interface signals to provide a 4-wire unbal-
anced, asynchronous modem interface ASC1 conforming to ITU-T V.24 protocol DCE signal-
ling. The electrical characteristics do not comply with ITU-T V.28. The significant levels are 0V
(for low data bit or active state) and 1.8V (for high data bit or inactive state).
The following four GPIO lines are by default configured as ASC1 interface signals:
GPIO16 --> RXD1, GPIO17 --> TXD1, GPIO18 --> RTS1 and GPIO19 --> CTS1.
BGS5 is designed for use as a DCE. Based on the conventions for DCE-DTE connections it
communicates with the customer application (DTE) using the following signals:
• Port TXD @ application sends data to module’s TXD1 signal line
• Port RXD @ application receives data from the module’s RXD1 signal line
Figure 4: Serial interface ASC1
Features
• Includes only the data lines TXD1 and RXD1 plus RTS1 and CTS1 for hardware hand-
shake.
• On ASC1 no RING line is available.
• Configured for 8 data bits, no parity and 1 or 2 stop bits.
• ASC1 can be operated at fixed bit rates from 1,200 bps to 921600 bps.
• Autobauding supports bit rates from 1200bps up to 230400bps.
• Supports RTS1/CTS1 hardware flow control. The hardware hand shake line RTS1 has an
internal pull down resistor causing a low level signal, if the line is not used and open.
Although hardware flow control is recommended, this allows communication by using only
RXD and TXD lines.