37.7.19 USB Max Data TX Register
| Symbol | Description | Symbol | Description | Symbol | Description |
|---|---|---|---|---|---|
| R | Readable bit | HC | Cleared by Hardware | (Grey cell) | Unimplemented |
| W | Writable bit | HS | Set by Hardware | X | Bit is unknown at Reset |
| K | Write to clear | S | Software settable bit | — | — |
| Name: | TXMAXP |
| Offset: | 0x1010 |
| Reset: | 0x0000 |
| Property: | PAC Write-Protection |
| Bit | 15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | |
| MULT[4:0] | TXMAXP[10:8] | ||||||||
| Access | R/W | R/W | R/W | R/W | R/W | R/W | R/W | R/W | |
| Reset | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | |
| Bit | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 | |
| TXMAXP[7:0] | |||||||||
| Access | R/W | R/W | R/W | R/W | R/W | R/W | R/W | R/W | |
| Reset | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | |
Bits 15:11 – MULT[4:0] Multiplier Control bits
For Isochronous/Interrupt endpoints or of packet splitting on Bulk endpoints, multiplies TXMAXP by MULT+1 for the payload size.
For Bulk endpoints, MULT can be up to 32 and defines the number of "USB" packets of the specified payload into which a single data packet placed in the FIFO should be split, prior to transfer. The data packet is required to be an exact multiple of the payload specified by TXMAXP.
For Isochronous/Interrupts endpoints operating in Hi-Speed mode, MULT may be either 2 or 3 and specifies the maximum number of such transactions that can take place in a single microframe.
Bits 10:0 – TXMAXP[10:0] Maximum TX Payload per Transaction Control bits
This field sets the maximum payload (in bytes) transmitted in a single transaction. The value is subject to the constraints placed by the USB Specification on packet sizes for Bulk, Interrupt and Isochronous transfers in Full-Speed and Hi-Speed operations.
TXMAXP must be set to an even number of bytes for proper interrupt generation in DMA Mode 1.