/*********************************************************************** * SEGGER Microcontroller GmbH * * The Embedded Experts * ************************************************************************ * * * (c) SEGGER Microcontroller GmbH * * All rights reserved * * www.segger.com * * * ************************************************************************ * * ************************************************************************ * * * * * Licensing terms * * * * This software may be distributed to your customers free of charge. * * This grant of redistribution does not entitle YOU or enduser to * * receive from SEGGER hard-copy documentation, technical support, * * phone assistance, or enhancements or updates to the Software unless * * a specific agreement clearly states otherwise. * * * * * * THIS SOFTWARE IS PROVIDED BY COPYRIGHT HOLDER "AS IS" AND ANY * * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR * * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL COPYRIGHT HOLDER BE * * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, * * OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, * * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR * * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY * * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT * * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE * * USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH * * DAMAGE. * * * ************************************************************************ -------------------------- END-OF-HEADER ----------------------------- Purpose: Example showing the SWD => JTAG switching sequence as documented by ARM. Literature: [1] J-Link documentation: https://wiki.segger.com/J-Link_script_files [2] Cortex-M Technical Reference Manual */ /********************************************************************* * * Constants * ********************************************************************** */ // // Data to be sent to target (LSB first!). // // SWD => JTAG Switching sequence. // const U8 _aTMSSwitch[] = { 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, // JTAG/SWD line reset. 0x3C, 0xE7, // SWD -> JTAG switching sequence. 0xFF, 0x00 // Ensures that JTAG is in Idle state. }; const U8 _aTDISwitch[] = { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // Nothing to do (NTD) 0x00, 0x00, // NTD 0x00, 0x00 // NTD }; // // Read IDCODE. // Technically we are in IDCODE state already, but for the sake of this example, we will still switch to it // const U8 _aTMSReadID[] = { 0x03, // Go to "Capture-IR" and send IDCODE command (b'1100_0000: Idle => DR-Scan => IR-Scan => Capture-IR => Shift-IR => 4x Shift-IR) 0x70, // Send BYPASS command and go to Capture-DR (b'0000_1110: 4x Shift-IR => Exit1-IR => Update-IR => DR-Scan => Capture-DR) 0x00, 0x00, 0x00, 0x00, // Receive ID (4x 0x00: 32x Shift-DR) 0x03 // Return to Idle (b'1100_0000: Exit1-DR => Update-DR => 6x Idle). }; const U8 _aTDIReadID[] = { 0xE0, // 4 bits NTD + send READIDCODE command LSB (b'1110 => b'0111 (LSB)) 0x0F, // Send BYPASS command (b'1111) + 4bits NTD 0x00, 0x00, 0x00, 0x00, // NTD 0x00 // NTD }; /********************************************************************* * * Static code * ********************************************************************** */ /********************************************************************* * * _SWD_BufGetU32 * * Function descripton * Get unsigned 32 bit value from an SWD transmission buffer. * * Parameters * pData Buffer containing data read via SWD. * Pos Position from which the U32 should be read. * * Return value * >= 0: U32 read. */ static U32 _JTAG_BufGetU32(U8* pData, U32 Pos) { U32 iStart; U32 BitsRem; U32 Shift; U32 Result; U8 v; U8 Mask; iStart = Pos >> 3; // Divide by 8. BitsRem = (Pos & 7); // Modulo 8 to get remaining bits. Shift = 31 - (BitsRem - 1); // Get required shift. Mask = 0xFF >> (8 - BitsRem); // Get mask for remaining bits Result = 0 | (*(pData + iStart + 0) << 0) | (*(pData + iStart + 1) << 8) | (*(pData + iStart + 2) << 16) | (*(pData + iStart + 3) << 24) ; Result >>= BitsRem; // Shift to be 32-bit aligned. if (BitsRem != 0) { // We have remaining bits? => Add them. v = *(pData + iStart + 4); v &= Mask; Result |= (v << Shift); } return Result; } /********************************************************************* * * Global functions * ********************************************************************** */ /********************************************************************* * * InitTarget() * * Function description * If present, called right before performing generic connect sequence. * Usually used for targets which need a special connect sequence. * E.g.: TI devices with ICEPick TAP on them where core TAP needs to be enabled via specific ICEPick sequences first. * * Return value * >= 0: O.K. * < 0: Error * * Notes * (1) Must not use high-level API functions like JLINK_MEM_ etc. * (2) For target interface JTAG, this device has to setup the JTAG chain + JTAG TAP Ids. */ int InitTarget(void) { U32 Id; U8 aTDO[16]; // // Execute Switching sequence // JLINK_SYS_Report(" Executing SWD => JTAG switching sequence..."); JLINK_JTAG_ReadWriteBits(&_aTDISwitch[0], &_aTMSSwitch[0], &aTDO[0], 11 * 8); // // Execute ReadID command // NumBits Meaning // 8 Execute READID command // 4 Execute BYPASS command // 4 Go to Shift-DR // 4*8 Receive ID // 8 Return to Idle state. // => IDCODE can be from position 17 of the TDO buffer. // JLINK_JTAG_ReadWriteBits(&_aTDIReadID[0], &_aTMSReadID[0], &aTDO[0], 7 * 8); Id = _JTAG_BufGetU32(&aTDO[0], 2 * 8 + 1); if ((Id & 0x0FF00FFF) == 0xBA00477) { JLINK_SYS_Report1(" Found JTAG-DP with ID ", Id); } else { JLINK_SYS_Report1(" No valid JTAG-DP found. Expected pattern 0xBA00477, found pattern: ", Id); } return 0; } /*************************** end of file ****************************/