MAX14830_15 Datasheet, PDF (45/68 Pages) Maxim Integrated Products – Quad Serial UART with 128-Word FIFOs

MAX14830
Quad Serial UART with 128-Word FIFOs
TxFIFOLvl—Transmit FIFO Level Register
ADDRESS:
MODE:
BIT
NAME
RESET
7
TxFL7
0
0x11
R
6
TxFL6
0
5
TxFL5
0
4
TxFL4
0
3
TxFL3
0
2
TxFL2
0
1
TxFL1
0
0
TxFL0
0
Bits 7–0: TxFL[n]
The TxFIFOLvl register represents the current number of words in the transmit FIFO whenever the transmit UART is
idle. When the transmit UART actively sends out characters, the value in this register can sometimes be inaccurate if
this register is read at the same time that the transmit UART updates the transmit FIFO. First disable the transmitter to
get an accurate value. To manage the transmit FIFO even when the transmit UART is active, do not use this register to
determine transmit FIFO state. Rather, use the TFifoEmpty bit or the TFifoTrigInt bits.
RxFIFOLvl—Receive FIFO Level Register
ADDRESS:
0x12
MODE:
R
BIT
7
6
5
4
3
2
1
0
NAME
RxFL7
RxFL6
RxFL5
RxFL4
RxFL3
RxFL2
RxFL1
RxFL0
RESET
0
0
0
0
0
0
0
0
Bits 7–0: RxFL[n]
The RxFIFOLvl register represents the current number of words in the receive FIFO whenever the receive UART is
idle. When the receive UART actively receives characters, the value in this register can sometimes be inaccurate if this
register is read at the same time that the receive UART updates the receive FIFO. To manage the receive FIFO even
when the receive UART is active, do not use this register to determine receive FIFO state. Use the RFIFOEmptyInt bit,
the RxTrgInt bit, and the RTimeOut bit instead.
FlowCtrl—Flow Control Register
ADDRESS:
MODE:
0x13
R/W
BIT
NAME
RESET
7
SwFlow3
0
6
SwFlow2
0
5
SwFlow1
0
4
SwFlow0
0
3
SwFlowEn
0
2
GPIAddr
0
1
AutoCTS
0
0
AutoRTS
0
Bits 7–4: SwFlow[n]
The SwFlow[n] bits configure auto software flow control and/or special character detection in combination with the char-
acters defined in the XON1, XON2, XOFF1, and/or XOFF2 registers. See Table 4.
FlowCtrl[n] selects which of the XON1, XON2, XOFF1, or/and XOFF2 characters are used for special character detec-
tion and/or auto flow control. If auto receiver flow control is enabled through SwFlowEn and FlowCtrl[n], the XON and
XOFF characters that the MAX14830 receives are filtered out and are not put into the RxFIFO. Set the SwFlowEn bit to
0 and set MODE2[4] to 1 to enable special character detection. Under these conditions, auto flow transmit flow control
is not used.
If both special character detection (MODE2[4]) and automatic software flow control (FlowCtrl[3]) are to be enabled,
XON1 and XOFF1 define the auto flow control characters while XON2 and XOFF2 define the special character detection
characters.
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