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