NXP Semiconductors freescale K51 Series Reference Manual

48.3.25 UART 7816 Interrupt Status Register (UARTx_IS7816)The IS7816 register provides a mechanism to read and clear the interrupt flags. All flags/interrupts are cleared by writing a "1" to the bit location. Writing a "0" has no effect. Allbits are "sticky", meaning they only indicate that the flag condition occurred since the lasttime the bit was cleared not that the condition currently exists. The status flags are setregardless of if the corresponding bit in the IC7816 is set or cleared, the IC7816 onlycontrols if a interrupt is issued to the host processor. This register is specific to 7816functionality and the values in this register have no affect on UART operation and shouldbe ignored if 7816E is not set/enabled. This register may be read or written at anytime.Addresses: UART0_IS7816 is 4006_A000h base + 1Ah offset = 4006_A01AhUART1_IS7816 is 4006_B000h base + 1Ah offset = 4006_B01AhUART2_IS7816 is 4006_C000h base + 1Ah offset = 4006_C01AhUART3_IS7816 is 4006_D000h base + 1Ah offset = 4006_D01AhUART4_IS7816 is 400E_A000h base + 1Ah offset = 400E_A01AhUART5_IS7816 is 400E_B000h base + 1Ah offset = 400E_B01AhBit 7 6 5 4 3 2 1 0Read WT CWT BWT INITD 0 GTV TXT RXTWriteReset 0 0 0 0 0 0 0 0UARTx_IS7816 field descriptionsField Description7WTWait Timer InterruptThis flag indicates that the wait time, the time between the leading edge of a character being transmittedand the leading edge of the next response character has exceeded the programed value. This flag onlyasserts when C7816[TTYPE] = 0. This interrupt is cleared by writing `1'.0 Wait time (WT) has not been violated.1 Wait time (WT) has been violated.6CWTCharacter Wait Timer InterruptThis flag indicates that the character wait time, the time between the leading edges of two consecutivecharacters in a block has exceed the programed value. This flag only asserts when C7816[TTYPE] = 1.This interrupt is cleared by writing `1'.0 Character wait time (CWT) has not been violated.1 Character wait time (CWT) has been violated.5BWTBlock Wait Timer InterruptThis flag indicates that the block wait time, the time between the leading edge of first received characterof a block and the leading edge of the last character the previously transmitted block. This flag onlyasserts when C7816[TTYPE] = 1.This interrupt is cleared by writing '1'.Table continues on the next page...Chapter 48 Universal Asynchronous Receiver/Transmitter (UART)K51 Sub-Family Reference Manual, Rev. 6, Nov 2011Freescale Semiconductor, Inc. 1253