DAP_SWD_Sequence

Generate SWD sequence and output on SWDIO or capture input from SWDIO data.

Note

The DAP_SWD_Sequence is available for CMSIS-DAP version 1.2 and higher. Refer to DAP_Info for more information on how to query the CMSIS-DAP version.

The DAP_SWD_Sequence Command is used to generate special sequences in SWD mode on the pins SWCLK and SWDIO. For example, for SWD multi-drop target selection (see picture) it is required to put the SWDIO pin to input mode (where it is not driven).

SWD sequence for multi-drop target selection

• For mode=0 (output: SWDIO is driven), the data for the SWDIO pin are part of the DAP_SWD_Sequence Command.
• For mode=1 (input: SWDIO is not driven), the data from the SWDIO pin are captured and returned as part of the DAP_SWD_Sequence Response.

DAP_SWD_Sequence Command:

| BYTE | BYTE **********| BYTE *********| BYTE ******|
> 0x1D | Sequence Count | Sequence Info | SWDIO Data |
|******|****************|

• Sequence Count: Number of Sequences
• Sequence Info: Contains number of SWCLK cycles and SWDIO mode
  • Bit 5 .. 0: Number of TCK cycles: 1 .. 64 (64 encoded as 0)
  • Bit 6: reserved
  • Bit 7: mode: 0=output (SWDIO Data in command), 1=input (SWDIO Data in response)
• SWDIO Data (only for output mode): Data generated on SWDIO
  • One bit for each TCK cycle
  • LSB transmitted first, padded to BYTE boundary

DAP_SWD_Sequence Response:

| BYTE | BYTE **| BYTE ******|
< 0x1D | Status | SWDIO Data |
|******|********|++++++++++++|

• SWDIO Data (only for input mode): Data captured from SWDIO
  • One bit for each SWCLK cycle for input mode
  • LSB received first, padded to BYTE boundary
• Status: Response Status