SWCU192 November 2021 CC1312R7 , CC1352P7 , CC2652P7 , CC2652R7
7.2 cJTAG
This module implements IEEE 1149.7 compliant compact JTAG (cJTAG) adapter, which runs a 2-pin communication protocol on top of a IEEE 1149.1 JTAG test access port (TAP). The 2-pin JTAG mode using only TCK and TMS is the default configuration after power up. The cJTAG configuration in the CC13x2x7 and CC26x2x7 device platform implements a subset of class 4 feature scan modes. Class 4 inherits features from classes 0, 1, 2, and 3 (except the features mentioned in Table 7-2). Figure 7-3 shows a conceptual diagram of the cJTAG module.
Figure 7-3 cJTAG Conceptual Diagram
- Class 0: Strict compliance to IEEE 1149.1 specification with internal TAP selection
- Class 1: Adds cJTAG command protocol, some optional discrete commands
- Class 2: Adds serial select capability
- Class 3: Adds JTAG star configuration, controller IDs and scan selection directives
- Class 4: Adds advanced scan protocols
Table 7-2 lists the features in IEEE 1149.7 that are supported in the CC13x2x7 and CC26x2x7 device platform. The cJTAG module in the CC13x2x7 and CC26x2x7 device platform supports 12 scan formats. The scan formats use a variety of compression protocols ranging from 1 to 4 clocks per bit to serialize each packet.
| IEEE 1149.7 Feature | Device Support Through cJTAG | Comment | |
|---|---|---|---|
| Configuration | Class 4 TAP | Yes | Supports 2-pin operation |
| Class 5 TAP | No | Data and custom channels for background data transfer | |
| Optional components | FRST | No | Functional reset |
| TRST | No | Test reset | |
| RDBK capability | No | Readback of register data | |
| Aux pin functions | Yes | Reuse of TDI and TDO pins | |
| TCKWID | No | Programmable TCK width | |
| Power control | Power down logic | No | Power down logic capability for cJTAG module |
| Scan formats | JScan0 | Yes | Parallel mode |
| JScan1 | Yes | Parallel with firewall | |
| JScan2 | Yes | Parallel with super bypass select | |
| JScan3 | Yes | Parallel with register select | |
| MScan | No | Multidevice mode, supports stalls | |
| OScan0 | Yes | Supports stalls | |
| OScan1 | Yes | Non-stall mode | |
| OScan2 | Yes | Bidirectional transfers, pipelined | |
| OScan3 | Yes | Host to target only, pipelined | |
| OScan4 | Yes | Supports stalls | |
| OScan5 | Yes | Pipelined | |
| OScan6 | Yes | Bidirectional transfers, pipelined | |
| OScan7 | Yes | Host to target only, pipelined | |
| SScan0 | No | Segmented scan | |
| SScan1 | No | Segmented scan, supports stalls | |
| SScan2 | No | Segmented scan | |
| SScan3 | No | Segmented scan, supports stalls |
| Scan Format | Nonshift States | Shift States | ||||||
|---|---|---|---|---|---|---|---|---|
| OScan0 | nTDI | TMS | RDY | TDO | nTDI | TMS | RDY | TDO |
| OScan1 | nTDI | TMS | TDO | nTDI | TMS | TDO | ||
| OScan2 | TMS | nTDI | TMS | TDO | ||||
| OScan3 | TMS | nTDI | TMS | |||||
| OScan4 | nTDI | TMS | RDY | TDO | nTDI | RDY | TDO | |
| OScan5 | nTDI | TMS | TDO | nTDI | TDO | |||
| OScan6 | TMS | nTDI | TMS(1) | TDO | ||||
| OScan7 | TMS | nTDI | ||||||