UART/ Serial Interfaces Basic Information for Gemalto Modules
Tutorial, January 26, 2017 - 5:11pm, 3084 views
The Gemalto Module can support 8-line UART for ASC0 and 4-line UART for ASC1.
In general, the module provids two UART interfaces, named ASC0
and ASC1. In default mode, ASC0 is the AT command channel and
four ASC1 lines are alternatively configured as GPIO.
You can use the ATˆSCFG command to configure the ASC0 to 8-line modem port,
or to change the GPIOs to ASC1 function or SPI interface.
You can have the following combinations of the UART ports:
- AT channel + GPIO
- AT channel + AT channel
- AT channel + SPI
- Data channel + GPIO
- Data channel + AT channel
- IData channel + SPI
Meanwhile, you can also design 2-line (without flow-control),
4-line (with flow-control) and 8-line (full modem) UART interface at the module
Here are the line definitions
Data line: Tx/Rx
Flow-control line: RTS/CTS
Modem state indication: DTR/DSR/DCD/RING (only available for ASC0)
NOTE: TX and RTS are module inputs.
Regarding the definitions above, you need to be careful with the DTR line.
This line is not used as flow-control, it should be used as state
The properties of the Interface are:
- Baudrate, eg: 961200, 115200, 9600, etc,.
- Frame length, eg: 8bit, 7bit
- Parity bit, eg: N/E/O, if frame lenght not equal to 9 for E/O
- Stop bit, eg: 1bit or 2bit
- Function lines, include:
The following table shows you the structure of a normal UART frame:
You can monitor the frame with a scope and it will look like this. The UART frame shows here the command 'AT'
Often people are confused how to setup the baudrate of the module. You can simply setup with AT+IPR the baudrate:
AT+IPR is a feature which can configure the module UART port
Where fkernel = 104MHz, DEC, INC means decrease and increase
fractional divider value and BCRV is for baud-rate counter
reloaded value. Regarding the above equation, the module can support
even non-standard baud-rate just by adjusting the parameters.
AT+ICF provides the module a facility to configure not only baud rate
but also other properties of UART port, like:
- Frame length
- IParity bit
- Stop bit
In addition, after the module introduced ICF function, auto baud
feature also be extended, and becomes to a full enhancement.
Both ICF and IPR settings are dedicate for each port and each
port has its own profile to store these settings, means, if use ICF or
IPR configure current port, only influence current port
In power consumption sensitive use cases, you need to keep the module
under low power mode.
This can be configured by:
ATˆ SPOW=<mode>,<wakeup timeout>,<awake>
When the UART port is in polling mode, it can be waked up:
- Incoming data on UART port (polled)
- RTS toggle at host side
- Use other ports change ˆSPOW setting
However, when the UART port is disabled, it can only be
activated by another port.