Specifications

UNBOUND_LOCAL: Are you trying to use a variable before you put something in it?
INVALID_FUNC_ARGS: Are you passing the wrong type of parameters to a function?
Are you passing the wrong quantity of parameters?
INVALID_SUBSCRIPT: Are you trying to access str[3] when str = 'ABC'?
(When str = 'ABC', str[0] is 'A', str[1] is 'B', and str[2] is 'C')
EXCEEDED_MAX_LOCAL_STACK: Do you have too many local variables?
ALLOC_FAIL: Are you trying to keep too many string results? As of version 2.2 you are no longer
limited to a single buffer for each type of string operation, but they are still limited in number.
MAX_PACKET_SIZE_EXCEEDED: Are you passing too large of a string value?
MAX_STRING_SIZE_EXCEEDED: Have you created a dynamic string too large for your platform?
Refer to the section for your specific platform (at the back of this document) for detailed buffer limits.
flowControl(uart, isEnabled, isTxEnable) – Enable/disable flow control
The flowControl() function allows you to disable or enable UART hardware handshaking.
Parameter uart is an integer that specifies which UART (0 or 1).
Parameter isEnabled is a boolean which turns hardware flow control on or off.
Parameter isTxEnable is an optional parameter that only matters if parameter isEnabled is True. If
isEnabled is False, then isTxEnable has no effect.
When flow control is enabled for UART0, GPIO pins 5 and 6 become CTS and RTS pins for that
UART. When flow control is enabled for UART1, GPIO pins 9 and 10 become CTS and RTS pins for
that UART.
When flow control is ON, the RFE monitors the RTS pin from the attached serial device. As long as
the RFE sees the RTS pin low, the RFE will continue sending characters to the attached serial device
(assuming it has any characters to send). If the RFE sees the RTS pin go high, then it will stop sending
characters to the attached serial device.
When flow control is OFF (isEnabled = False), the RTS and CTS pins are ignored.
The benefit of turning flow control off is that it frees up two more pins (per UART) for use as other
I/O. The drawback of turning off flow control is that characters can be dropped.
Once enabled via the isEnabled parameter, the actual behavior of the CTS pin depends on the
isTxEnable parameter. When isTxEnable is False, CTS acts as Clear To Send (described below). When
isTxEnable is True, CTS instead acts as a TXENA pin.
NOTE – To maintain compatibility with scripts from version 2.1, the isTxEnable parameter does not
have to be explicitly specified. If you leave it off, SNAP acts as if you explicitly specified False.
When flow control is ON (isEnabled = True) and isTxEnable is False, the SNAP Engine controls the
CTS pin to indicate if it can accept more data. The CTS pin is low if the RFE can accept more
SNAP Reference Manual Document Number 600-0007K Page 47 of 202