UART UART Low Power Registers 0x40042000 0x00 0x1000 registers CTRL Control register 0x0000 RX_THD_VAL This field specifies the depth of receive FIFO for interrupt generation (value 0 and > 16 are ignored) 0 4 PAR_EN Parity Enable 4 1 PAR_EO when PAREN=1 selects odd or even parity odd is 1 even is 0 5 1 PAR_MD Selects parity based on 1s or 0s count (when PAREN=1) 6 1 CTS_DIS CTS Sampling Disable 7 1 TX_FLUSH Flushes the TX FIFO buffer. This bit is automatically cleared by hardware when flush is completed. 8 1 RX_FLUSH Flushes the RX FIFO buffer. This bit is automatically cleared by hardware when flush is completed. 9 1 CHAR_SIZE Selects UART character size 10 2 5bits 5 bits 0 6bits 6 bits 1 7bits 7 bits 2 8bits 8 bits 3 STOPBITS Selects the number of stop bits that will be generated 12 1 HFC_EN Enables/disables hardware flow control 13 1 RTSDC Hardware Flow Control RTS Mode 14 1 BCLKEN Baud clock enable 15 1 BCLKSRC To select the UART clock source for the UART engine (except APB registers). Secondary clock (used for baud rate generator) can be asynchronous from APB clock. 16 2 Peripheral_Clock apb clock 0 External_Clock Clock 1 1 CLK2 Clock 2 2 CLK3 Clock 3 3 DPFE_EN Data/Parity bit frame error detection enable 18 1 BCLKRDY Baud clock Ready read only bit 19 1 UCAGM UART Clock Auto Gating mode 20 1 FDM Fractional Division Mode 21 1 DESM RX Dual Edge Sampling Mode 22 1 STATUS Status register 0x0004 read-only TX_BUSY Read-only flag indicating the UART transmit status 0 1 RX_BUSY Read-only flag indicating the UART receiver status 1 1 RX_EM Read-only flag indicating the RX FIFO state 4 1 RX_FULL Read-only flag indicating the RX FIFO state 5 1 TX_EM Read-only flag indicating the TX FIFO state 6 1 TX_FULL Read-only flag indicating the TX FIFO state 7 1 RX_LVL Indicates the number of bytes currently in the RX FIFO (0-RX FIFO_ELTS) 8 4 TX_LVL Indicates the number of bytes currently in the TX FIFO (0-TX FIFO_ELTS) 12 4 INT_EN Interrupt Enable control register 0x0008 RX_FERR Enable Interrupt For RX Frame Error 0 1 RX_PAR Enable Interrupt For RX Parity Error 1 1 CTS_EV Enable Interrupt For CTS signal change Error 2 1 RX_OV Enable Interrupt For RX FIFO Overrun Error 3 1 RX_THD Enable Interrupt For RX FIFO reaches the number of bytes configured by RXTHD 4 1 TX_OB Enable Interrupt For TX FIFO has one byte remaining 5 1 TX_HE Enable Interrupt For TX FIFO has half empty 6 1 INT_FL Interrupt status flags Control register 0x000C RX_FERR Flag for RX Frame Error Interrupt. 0 1 RX_PAR Flag for RX Parity Error interrupt 1 1 CTS_EV Flag for CTS signal change interrupt (hardware flow control disabled) 2 1 RX_OV Flag for RX FIFO Overrun interrupt 3 1 RX_THD Flag for interrupt when RX FIFO reaches the number of bytes configured by the RXTHD field 4 1 TX_OB Flag for interrupt when TX FIFO has one byte remaining 5 1 TX_HE Flag for interrupt when TX FIFO is half empty 6 1 CLKDIV Clock Divider register 0x0010 CLKDIV Baud rate divisor value 0 20 OSR Over Sampling Rate register 0x0014 OSR OSR 0 3 TXPEEK TX FIFO Output Peek register 0x0018 DATA Read TX FIFO next data. Reading from this field does not affect the contents of TX FIFO. Note that the parity bit is available from this field. 0 8 PNR Pin register 0x001C CTS Current sampled value of CTS IO 0 1 read-only RTS This bit controls the value to apply on the RTS IO. If set to 1, the RTS IO is set to high level. If set to 0, the RTS IO is set to low level. 1 1 FIFO FIFO Read/Write register 0x0020 DATA Load/unload location for TX and RX FIFO buffers. 0 8 RX_PAR Parity error flag for next byte to be read from FIFO. 8 1 DMA DMA Configuration register 0x0030 TX_THD_VAL TX FIFO Level DMA Trigger If the TX FIFO level is less than this value, then the TX FIFO DMA interface will send a signal to system DMA to notify that TX FIFO is ready to receive data from memory. 0 4 TX_EN TX DMA channel enable 4 1 RX_THD_VAL Rx FIFO Level DMA Trigger If the RX FIFO level is greater than this value, then the RX FIFO DMA interface will send a signal to the system DMA to notify that RX FIFO has characters to transfer to memory. 5 4 RX_EN RX DMA channel enable 9 1 WKEN Wake up enable Control register 0x0034 RX_NE Wake-Up Enable for RX FIFO Not Empty 0 1 RX_FULL Wake-Up Enable for RX FIFO Full 1 1 RX_THD Wake-Up Enable for RX FIFO Threshold Met 2 1 WKFL Wake up Flags register 0x0038 RX_NE Wake-Up Flag for RX FIFO Not Empty 0 1 RX_FULL Wake-Up Flag for RX FIFO Full 1 1 RX_THD Wake-Up Flag for RX FIFO Threshold Met 2 1