jtag
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jtag [2016/02/02 10:00] – add j-link kingkevin | jtag [2018/01/06 12:09] – [Altera USB-Blaster] fix typo kingkevin | ||
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- | Here I will describe my experiences with JTAG and how I use it. | + | JTAG is a technology to test integrated circuits, mostly micro-controllers and CPUs. |
- | + | It allows to do hardware debugging: | |
- | JTAG is a technology to test electronics. | + | SWD is a more modern version of JTAG and only requires 2 pins instead of 4[+1].\\ |
- | It allows to do hardware debugging: | + | SWJ is a combination of Serial Wire Debug (SWD) and JTAG. |
+ | But they provide the same logical functions. | ||
On one side this functionality must be included in the target device. | On one side this functionality must be included in the target device. | ||
- | Most 32 bits micro-controllers | + | The Debug Port is often called JTAG-DP for JTAG and SW-DP for SWD. |
- | On the other side you need a JTAG adapter so the host can speak to the device | + | SWJ capable |
- | JTAG adapters can go from cheap (<5$) to expensive (> | + | Most 32 bits micro-controllers and SoCs have one of both (or both). |
- | ===== JTAG adapters | + | On the other side you need a SWJ adapter so the host can speak to the device using the JTAG and/or SWD protocol. |
+ | SWJ adapters | ||
- | These are the main JTAG adapters | + | ====== SWJ adapters |
- | ==== ST-Link v2 (clone) | + | These are the main SWJ adapters I am using. |
+ | |||
+ | ===== ST-Link v2 ===== | ||
The [[http:// | The [[http:// | ||
+ | It supports JTAG, SWD, and SWIM (for STM8). | ||
- | I have two cheap clones: | + | These SWJ adapters are based STM32F1xx ARM Cortex M3 micro-controllers. |
- | * one from [[http:// | + | |
- | {{: | + | |
- | {{: | + | |
- | {{: | + | |
- | {{: | + | |
- | {{: | + | |
- | * one [[http:// | + | |
- | {{: | + | |
- | {{: | + | |
- | {{: | + | |
- | {{: | + | |
- | + | ||
- | These devices use the Serial Wire Debug (SWD) protocol. | + | |
- | This is newer variant of JTAG which requires only 2 signal lines instead of 4+. | + | |
- | But but aware, they both have different pinouts on the connector. | + | |
- | The second one offers 2 more power ports at the expense of JTAG TDI and TDO/SWO. | + | |
- | + | ||
- | These JTAG adapters are based STM32F1xx ARM Cortex M3 micro-controllers. | + | |
And ironically enough I in turn use them to program and debug STM32F1xx ARM Cortex M3 micro-controllers. | And ironically enough I in turn use them to program and debug STM32F1xx ARM Cortex M3 micro-controllers. | ||
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This has only to be done once, before the device is plugged in to be used: | This has only to be done once, before the device is plugged in to be used: | ||
<code bash> | <code bash> | ||
- | echo -n 'STM32F1xx ARM Cortex M3 micro-controllers' | sudo tee -a / | + | echo -n 'ST-Link V2 SWJ adapter' | sudo tee -a / |
echo -n ' | echo -n ' | ||
sudo udevadm control --reload-rules | sudo udevadm control --reload-rules | ||
Line 68: | Line 55: | ||
</ | </ | ||
- | ==== Altera USB-Blaster (clone) ==== | + | I am using cheap clones. |
- | The [[https:// | + | ==== ST-LINK/V2 clone ==== |
- | It is often used to flash FPGA, but is a general purpose JTAG adapter. | + | |
- | I have a cheap [[http:// | + | {{:jtag: |
- | The original uses FTDI FT245 and MAX CPLD chips. | + | {{: |
- | This one uses a Silicon Labs C8051F321 micro-controller and a 74LVC125 quad buffer, but there are many other clone variants. | + | {{: |
+ | {{: | ||
+ | {{: | ||
- | {{:jtag:dsc02418.jpg?0x100|device | + | This is a complete rip-off of the [[http:// |
- | {{:jtag:dsc02419.jpg?0x100|device | + | It comes in the same box, with the same cables, the enclosure is the same, even the board name has been taken over (MB936), but the board isn't the same. |
- | {{:jtag:dsc02420.jpg?0x100|PCB front}} | + | The BOM doesn' |
- | {{:jtag:dsc02424.jpg?0x100|PCB back}} | + | The original adapter comes with ESD protection, protection resistors, and a transceiver to allow operating with target signal levels of 1.65V to 5.5V. |
+ | This is completely missing on the clone since the connector pins are directly connected to the micro-controller. | ||
+ | Thus it only supports target signal levels of 3.3V and sometimes 5V since the pins are 5V tolerant. | ||
+ | |||
+ | For $9 you can't expect more, and if you want a cheap adapter I recommend the other ones (see below). | ||
+ | |||
+ | ==== ST-LINK V2 aluminium ==== | ||
+ | |||
+ | These adapters come in a small dongle sized aluminium case. | ||
+ | They supports SWD, and SWIM (for STM8), but not JTAG. | ||
+ | |||
+ | At $2.5 they are the cheapest clones you can find.\\ | ||
+ | One trick to get this ridiculously low price is to use STM32F101 micro-controllers. | ||
+ | Compared to the STM32F103 micro-controllers they offer less functionalities, | ||
+ | Well this is because these micro-controllers use the same die, but if not all STM32F103 feature tests pass after production they get packages as STM32F101, but it seems that USB still works well enough. | ||
+ | At least this is my guess. | ||
+ | It would be interesting to check if the other STM32F103 peripherals normally not present on the STM32F101 work as well, but I wouldn' | ||
+ | After all, they are probably marked as STM32F101 for a good reason.\\ | ||
+ | Similarly the STM32F103C8 is only rated having 64 kB of flash because it didn't pass the flash test, compared to the 128 kB for the STM32F103CB, | ||
+ | |||
+ | Several board versions exist and it is hard to know what you will get. | ||
+ | Always check the pinout on the aluminium case since this also varies. | ||
+ | |||
+ | === 2014-06-22 ST-LINK V2 === | ||
+ | |||
+ | {{:jtag:alu_dongle_front.jpg?0x100|}} | ||
+ | {{: | ||
+ | {{: | ||
+ | |||
+ | I've also reversed the {{: | ||
+ | |||
+ | One other nice trick they used is to have twos LEDs on the same pin (PA9): | ||
+ | * when the pin is set to output high, only one LED lights up | ||
+ | * when the pin is set to output low, the other LED light up | ||
+ | * when set to input floating, both LEDs are off | ||
+ | * when PWM output is used, you can mix the two colors (red and blue) quite well due to the persistence of vision (also because the LEDs are next to each other and the small hole in the case is in the center). | ||
+ | |||
+ | === swapped === | ||
+ | |||
+ | {{: | ||
+ | {{:jtag:reverse-gnd_internal-front.jpg?0x100|}} | ||
+ | {{: | ||
+ | |||
+ | From the outside this looks very similar to the previous one, except that the connector pinout is very different (except for power) and there is only one LED.\\ | ||
+ | No markings are on the board. | ||
+ | |||
+ | === 2016-01-18 MX-LINK V2 === | ||
+ | |||
+ | {{:jtag:mx-link__case-front.jpg?0x100|}} | ||
+ | {{: | ||
+ | {{:jtag:mx-link__internal-back.jpg?0x100|}} | ||
+ | |||
+ | This one has an " | ||
+ | ==== Baite ==== | ||
+ | |||
+ | {{: | ||
+ | {{: | ||
+ | {{: | ||
+ | {{: | ||
+ | |||
+ | The [[http:// | ||
+ | |||
+ | They seem to use the same board also for several other programmers, | ||
+ | |||
+ | {{: | ||
+ | {{: | ||
+ | |||
+ | I've also reversed the board layout to get the {{: | ||
+ | The connector pins are all protected with 220 ohms resistors. | ||
+ | |||
+ | {{: | ||
+ | {{: | ||
+ | |||
+ | There is a newer version marked as " | ||
+ | * all pads for the micro-controller are present (there is even solder mask between them) | ||
+ | * they added a SWD port | ||
+ | * the STM32F103C8 has been replaced with a STM32F101CB, | ||
+ | * the passives are smaller | ||
+ | * the routing is horrible | ||
+ | |||
+ | ===== Black Magic Probe ===== | ||
+ | |||
+ | The [[https:// | ||
+ | Thus no need to have an OpenOCD server to control the SWJ adapter. | ||
+ | You can directly connect GDB to this adapter (over USB CDC ACM).\\ | ||
+ | It also comes with a UART port (over a second USB CDC ACM). | ||
+ | This is very useful while developing (for printf debugging). | ||
+ | |||
+ | The hardware comes with some disadvantages though: | ||
+ | * the ARM Cortex SWJ connector uses a small header (not very dupont-wire friendly) | ||
+ | * the separate UART is not always populated (UART is also available on the SWJ connector) | ||
+ | * it is expensive (> $50), but this price is quite reasonable since it supports the project | ||
+ | * it was sold out for quite some time, encouraging me to look for an alternative | ||
+ | |||
+ | Because the firmware is open source it is possible to port it to other hardware, and [[https:// | ||
+ | It has been [[https:// | ||
+ | It has also been [[http:// | ||
+ | So I decided to port it to the [[# | ||
+ | This has less power pins (who needs 2xGND, 2x5V, 3x3.3V anyway), but provides enough function pins to add UART (and SRST). | ||
+ | |||
+ | To build the firmware ([[https:// | ||
+ | <code bash> | ||
+ | git clone https:// | ||
+ | cd blackmagic | ||
+ | git submodule init | ||
+ | git submodule update | ||
+ | git checkout baite-platform | ||
+ | # if you are usgin GCC >= 7 | ||
+ | git cherry-pick 2ebcffa2a4911090b43c36594dae6b58d4bb2f27 | ||
+ | make | ||
+ | cd src | ||
+ | make clean | ||
+ | make PROBE_HOST=baite | ||
+ | </ | ||
+ | |||
+ | Now we need to re-flash the Baite dongle.\\ | ||
+ | As you can see on the {{: | ||
+ | But on the back of the board you can find test points so to program the device using the serial bootloader: | ||
+ | |||
+ | ^ pin ^ signal ^ | ||
+ | | 1 (square) | RX | | ||
+ | | 2 | TX | | ||
+ | | 3 | BOOT0 | | ||
+ | | 4 | +5V | | ||
+ | | 5 | GND | | ||
+ | |||
+ | Use any USB to UART converter and connect the corresponding pins to this port. | ||
+ | Don't power the Baite dongle over USB since it might then boot the normal application. | ||
+ | Instead let the USB to UART converter power it. | ||
+ | To start the serial bootloader when powering the dongle you need to set BOOT0 high by connecting it to +3.3V or DTR (or any high signal present on the USB to UART converter). | ||
+ | |||
+ | To flash the Black Magic firmware I used [[https:// | ||
+ | Since the flash is read/write protected you first need to clear these option bits. | ||
+ | |||
+ | <code bash> | ||
+ | # disable flash read protection | ||
+ | stm32flash -k / | ||
+ | # disable flash write protection | ||
+ | stm32flash -u / | ||
+ | # erase flash | ||
+ | stm32flash -o / | ||
+ | # flash the DFU bootloader | ||
+ | stm32flash -w src/ | ||
+ | # flash the main firmware | ||
+ | stm32flash -w src/ | ||
+ | </ | ||
+ | |||
+ | Since this adapter is based on an STM32F103C8 micro-controller with 64 kB of flash the DFU bootloader only advertises 56 kB of flash available for the main application. | ||
+ | Because the blackmagic firmware exceeds this size it will not be possible to flash it through if the DFU software doesn' | ||
+ | STM32F103C8 micro-controllers often have 128 kB of flash though, thus it is still possible to flash the blackmagic firmware using the serial bootloader (at address 0x08002000). | ||
+ | Verification during flashing ensured the whole firmware has been written successfully. | ||
+ | |||
+ | Unplug and re-plug the Baite dongle. | ||
+ | The adapter should be running the main application and two USB CDC ACM ports will appear. | ||
+ | |||
+ | You can re-flash the device from the main application using dfu-util (if you can bring dfu-util to ignore the size restriction): | ||
+ | <code bash> | ||
+ | dfu-util -d 1d50:6018 -s 0x08002000: | ||
+ | </ | ||
+ | |||
+ | Here is the new "BMP Baite" {{ : | ||
+ | ^ signal ^ pin ^ pin ^ signal ^ | ||
+ | | SRST | 1 | 2| +3.3V | | ||
+ | | +5V | 3 | 4 | JTCK/SWCLK | | ||
+ | | RX | 5 (key) | 6 | JTMS/SWDIO | | ||
+ | | GND | 7 | 8 | JTDO/ | ||
+ | | TX | 9 | 10 | JTDI | | ||
+ | |||
+ | **note**: the RX pin is pulled up by a 620 ohms resistor. Thus the TX connected to BMP Baite must by strong enough to drive it low (e.g. not like with the CH340 USB to UART converter). | ||
+ | |||
+ | If you connect SRST to the target NRST, it is even possible to reset the target board without having to press on the on-board reset button (of there is any): | ||
+ | <code bash> | ||
+ | gdb --eval-command=" | ||
+ | </ | ||
+ | ===== Altera USB-Blaster ===== | ||
+ | |||
+ | {{ : | ||
+ | |||
+ | The [[https:// | ||
+ | It is often used to flash FPGA, but is a general purpose JTAG adapter. | ||
:!: be aware that here the VCC{TARGET} pin has to be connected to a reference voltage used for the JTAG communication, | :!: be aware that here the VCC{TARGET} pin has to be connected to a reference voltage used for the JTAG communication, | ||
Line 93: | Line 260: | ||
</ | </ | ||
- | To be able to use it I had to recompile OpenOCD for the USB-Blaster to use libftdi (probable | + | To be able to use it I had to recompile OpenOCD for the USB-Blaster to use libftdi (maybe because it's a clone). |
<code bash> | <code bash> | ||
git clone http:// | git clone http:// | ||
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</ | </ | ||
- | ==== SEGGER J-Link | + | The original uses FTDI FT245 and MAX CPLD chips. |
+ | There are numerous clone variants, with various quality and voltage support. | ||
+ | |||
+ | ==== SiLabs USB-Blaster ==== | ||
+ | |||
+ | This one uses a Silicon Labs C8051F321 micro-controller and a 74LVC125 quad buffer (for signal voltages from 1.65 to 3.6 V). | ||
+ | |||
+ | {{: | ||
+ | {{: | ||
+ | |||
+ | ==== PIC USB-Blaster ==== | ||
+ | |||
+ | This one uses a Microchip PIC18F14 micro-controller and has no buffer (thus only supporting 5 V signals). | ||
+ | |||
+ | {{: | ||
+ | {{: | ||
+ | |||
+ | ==== ARMJISHU USB-Blaster ==== | ||
+ | |||
+ | This one uses a ST STM32F101 (as a STM32F103 with USB support) micro-controller and a 74HC244 octal-buffer (for signal voltages from 2.0 to 6.0 V). | ||
+ | |||
+ | {{: | ||
+ | {{: | ||
+ | |||
+ | I also reversed the {{: | ||
+ | It shows that the hardware can also drive the signals (at 3.3 V) in case Vcc_target is not connected, and you can add an uSD card slot or SPI flash. | ||
+ | I don't know if these features are supported in software. | ||
+ | |||
+ | {{: | ||
+ | {{: | ||
+ | ===== SEGGER J-Link | ||
The [[http:// | The [[http:// | ||
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That makes it the most complete JTAG adapter I have. | That makes it the most complete JTAG adapter I have. | ||
- | ===== tricks ===== | + | ====== tricks |
- | ==== scan chain ==== | + | ===== scan chain ===== |
JTAG devices are called Test Access Points (TAP). | JTAG devices are called Test Access Points (TAP). |
jtag.txt · Last modified: 2024/01/07 17:49 by 127.0.0.1