46.10.35 USART FIFO Mode Register
| Name: | FLEX_US_FMR |
| Offset: | 0x2A0 |
| Reset: | 0x00000000 |
| Property: | Read/Write |
| Bit | 31 | 30 | 29 | 28 | 27 | 26 | 25 | 24 | |
| RXFTHRES2[5:0] | |||||||||
| Access | R/W | R/W | R/W | R/W | R/W | R/W | |||
| Reset | 0 | 0 | 0 | 0 | 0 | 0 | |||
| Bit | 23 | 22 | 21 | 20 | 19 | 18 | 17 | 16 | |
| RXFTHRES[5:0] | |||||||||
| Access | R/W | R/W | R/W | R/W | R/W | R/W | |||
| Reset | 0 | 0 | 0 | 0 | 0 | 0 | |||
| Bit | 15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | |
| TXFTHRES[5:0] | |||||||||
| Access | R/W | R/W | R/W | R/W | R/W | R/W | |||
| Reset | 0 | 0 | 0 | 0 | 0 | 0 | |||
| Bit | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 | |
| FRTSC | RXRDYM[1:0] | TXRDYM[1:0] | |||||||
| Access | R/W | R/W | R/W | R/W | R/W | ||||
| Reset | 0 | 0 | 0 | 0 | 0 | ||||
Bits 29:24 – RXFTHRES2[5:0] Receive FIFO Threshold 2
| Value | Description |
|---|---|
| 0–32 | Defines the Receive FIFO threshold 2 value (number of bytes). The FLEX_US_FESR.RXFTHF2 flag will be set when Receive FIFO goes from “above” threshold state to “equal to or below” threshold state. |
Bits 21:16 – RXFTHRES[5:0] Receive FIFO Threshold
| Value | Description |
|---|---|
| 0–32 | Defines the Receive FIFO threshold value (number of bytes). The FLEX_US_FESR.RXFTHF flag will be set when Receive FIFO goes from “below” threshold state to “equal to or above” threshold state. |
Bits 13:8 – TXFTHRES[5:0] Transmit FIFO Threshold
| Value | Description |
|---|---|
| 0–32 | Defines the Transmit FIFO threshold value (number of bytes). The FLEX_US_FESR.TXFTHF flag will be set when Transmit FIFO goes from “above” threshold state to “equal to or below” threshold state. |
Bit 7 – FRTSC FIFO RTS Pin Control enable (Hardware Handshaking mode only)
See Hardware Handshaking for details.
| Value | Description |
|---|---|
| 0 | RTS pin is not controlled by Receive FIFO thresholds. |
| 1 | RTS pin is controlled by Receive FIFO thresholds. |
Bits 5:4 – RXRDYM[1:0] Receiver Ready Mode
If FIFOs are enabled, the FLEX_US_CSR.RXRDY flag behaves as follows.
| Value | Name | Description |
|---|---|---|
| 0 | ONE_DATA |
RXRDY will be at level ‘1’ when at least one unread data is in the receive FIFO. When DMA is enabled to transfer data and FLEX_US_MR.MODE9=0 (up to 8 bits to transfer on the line), the chunk of 1 byte must be configured in the DMA. If the transfer is performed by software, the access type must be defined as a byte. |
| 1 | TWO_DATA |
RXRDY will be at level ‘1’ when at least two unread data are in the receive FIFO. To minimize system bus load, when DMA is enabled to transfer data and FLEX_US_MR.MODE9=0 (up to 8 bits to transfer on the line), the chunk of 1 halfword (1 halfword carries 2 bytes) must be configured in the DMA (chunk size=1 and halfword access). If the transfer is performed by software, the access type can be defined as byte (1 byte per access, 2 accesses) or halfword (2 bytes per access, 1 single access). |
| 2 | FOUR_DATA |
RXRDY will be at level ‘1’ when at least four unread data are in the receive FIFO. To minimize system bus load, when DMA is enabled to transfer data and FLEX_US_MR.MODE9=0 (up to 8 bits to transfer on the line), the chunk of 1 word (1 word carries 4 bytes) must be configured in the DMA. If the transfer is performed by software, the access type can be defined as byte (1 byte per access, 4 accesses), halfword (2 bytes per access, 2 accesses) or word (4 bytes per access, 1 single access). |
Bits 1:0 – TXRDYM[1:0] Transmitter Ready Mode
If FIFOs are enabled, the FLEX_US_CSR.TXRDY flag behaves as follows.
| Value | Name | Description |
|---|---|---|
| 0 | ONE_DATA |
TXRDY will be at level ‘1’ when at least one data can be written in the transmit FIFO. When DMA is enabled to transfer data and FLEX_US_MR.MODE9=0 (up to 8 bits to transfer on the line), the chunk of 1 byte must be configured in the DMA. If the transfer is performed by software, the access type must be defined as a byte. |
| 1 | TWO_DATA |
TXRDY will be at level ‘1’ when at least two data can be written in the transmit FIFO. To minimize system bus load, when DMA is enabled to transfer data and FLEX_US_MR.MODE9=0 (up to 8 bits to transfer on the line), the chunk of 1 halfword (1 halfword carries 2 bytes) must be configured in the DMA. If the transfer is performed by software, the access type can be defined as byte (1 byte per access, 2 accesses) or halfword (2 bytes per access, 1 single access). |
| 2 | FOUR_DATA |
TXRDY will be at level ‘1’ when at least four data can be written in the transmit FIFO. To minimize system bus load, when DMA is enabled to transfer data and FLEX_US_MR.MODE9=0 (up to 8 bits to transfer on the line), the chunk of 1 word (1 word carries 4 bytes) must be configured in the DMA (chunk size=1 and word access). If the transfer is performed by software, the access type can be defined as byte (1 byte per access, 4 accesses), halfword (2 bytes per access, 2 accesses) or word (4 bytes per access, 1 single access). |