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; -------------------------------------------------------------------------------- ; @Title: How to use the Lauterbach debugger on a Raspberry Pi 2 target ; @Description: Board adaptation, GPIO configuration for JTAG, debugger start-up ; @Keywords: Cortex-A7, CORTEXA7MPCORE, enable, jtag, raspi2 ; @Author: HDA ; @Board: Raspberry Pi 2 ; @Chip: BCM2836 ; @Copyright: (C) 1989-2022 Lauterbach GmbH, licensed for use with TRACE32(R) only ; -------------------------------------------------------------------------------- ; $Id: readme.txt 18877 2022-02-02 07:04:07Z bschroefel $ The below was tested on a Raspberry Pi 2 Model B V1.1 board. Overview: The Raspberry Pi 2 Model B board has 4 Cortex-A7 cores plus a video core. When power on your RASPI2, the video core executes first-stage bootloader from ROM memory in order to mount the SD-card. The "bootcode.bin" and "start.elf" binaries, loaded from SD-card, are executed by the video core in order to prepare the RAM memory, load the "kernel.img" and releases the reset on the ARM CPUs. Then, the Cortex-A7 cores execute the "kernel.img". Unfortunately, JTAG pins are not connected by default to the outside world. The developer, needs to have a program that configures the alternate GPIO functions, so that the JTAG signals will show up on the J8 connector. During the debug session no reset might happen because this would cause the default configuration of the GPIOs and would disconnect the JTAG. The RASPI2 does not have a standard ARM20 JTAG-20 connector, so the user needs to build an adapter. RASPI2 J8 to JTAG-20 pin adapter : JTAG-20 signal GPIO pin ALT mode RASPI2 J8 pin 1 VREF J8-1 (3.3v) 3 nTRST GPIO22 ALT4 J8-15 5 TDI GPIO04 ALT5 J8-7 7 TMS GPIO27 ALT4 J8-13 9 TCK GPIO25 ALT4 J8-22 13 TDO GPIO24 ALT4 J8-18 4, 6,..,20 GND J8-6, 9, 14, 20, 25, 30, 34, 39 Configure the alternate GPIO functions: #define GPFSEL0 ((volatile unsigned int *) 0x3F200000) #define GPFSEL2 ((volatile unsigned int *) 0x3F200008) // GPIO22,24,25,27 alt4 -& nTRST,TDO,TCK,TMS *GPFSEL2 &= ~0x00e3f1c0; *GPFSEL2 |= 0x0061b0c0; // GPIO4 alt5 -& TDI *GPFSEL0 &= ~0x00007000; *GPFSEL0 |= 0x00002000; How to get this configuration executed: Rename enclosed "jtagenable.bin" to "kernel.img" and replace that file on the SD-card. It contains the configuration above and execute an infinite while loop (no operating system boot any-more). Further I had to remove/rename the existing kernel7.img to get it going. (Hint: The loader loads and starts "kernel.img" at 0x8000.) The real solution is to place the above GPIO configuration for JTAG in the program which runs after reset. Ensure that this configuration will not be changed by your program later. Or you can compile the module "jtagenable_linux_module.c" and run it from your linux distrubution. Debugger start-up: SYStem.CPU BCM2836 SYStem.mode attach Break.direct Alternatively run the enclosed demo program. home       back       Sitemap

Copyright © 2023 Lauterbach GmbH, Altlaufstr.40, 85635 Höhenkirchen-Siegertsbrunn, Germany   Impressum     Privacy Policy The information presented is intended to give overview information only. Changes and technical enhancements or modifications can be made without notice. Report Errors Last generated/modified: 14-Jun-2023