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Freescale Semiconductor, Inc.
Support Modules
flow_control
Call(s):
void flow_control (struct channel_t * channel);
Arguments:
Table 3-78. flow_control arguments
channel
Freescale Semiconductor, Inc...
Description:
in
Pointer to the Channel control data structure
This function performs Data Flow Control according to the S[18]
register settings.
The Soft Modem implements flow control by detecting that
Tx_uart_data[] is full enough (defined by the
UART_DATA_FLOW_STOP value, in “modem.h”) and then negates
the Request to Send (RTS) signal in the case of Hardware flow
control or sends a special character XOFF into the data stream in the
case of Software flow control, to stop the flow of data.
When the buffer Tx_uart_data[] is empty enough again (defined by
the UART_DATA_FLOW_START value , in “modem.h”), it asserts
the RTS signal in the case of Hardware flow control or sends the
special character XON into the data stream in the case of Software
flow control to restart the flow of data.
The problem with software flow control is that the characters used to
stop and start the flow of data can occur naturally in the data flow,
enabling software flow control instructions. Using software flow
control may prove satisfactory if you are transferring text files only.
Hardware flow control is much faster and much more reliable than
software flow control, so it is highly recommended to use this.
This function is called in state_machine().
Returns:
None.
Code example:
...
struct channel_t channel;
...
flow_control(&channel);
...
MOTOROLA
Chapter 3. Module Descriptions
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