Uwe Bonnes aff624b6e0 libftfdi: Allow to specify external resistor SWD connection.
More explanations in src/platforms/hosted/Readme.md
2020-09-04 11:49:13 +02:00

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# PC-Hosted BMP
Compile in src with "make PROBE_HOST=hosted"
## Description
PC-hosted BMP run on the PC and compiles as "blackmagic". When started,
it either presents a list of available probes or starts the BMP process
if either only one probe is attached to the PC or enough information is
given on the command line to select one of several probes.
When started without any other argument beside the probe selection, a
GDB server is started as port 2000 and up. Connect to the server as you would
connect to the BMP with the CDCACM GDB serial server. GDB functionality
is the same, monitor option may vary.
More arguments allow to
### Print information on the connected target
```
blackmagic -t
```
### Directly flash a binary file at lowest flash address
```
blackmagic <file.bin>
```
or with the -S argument at some other address
```
blackmagic -S 0x08002000 <file.bin>
```
### Read flash to binary file
```
blackmagic -r <file>.bin
```
### Verify flash against binary file
```
blackmagic -V <file>.bin
```
### Show more options
```
blackmagic -h"
```
## Used libraries:
### libusb
### libftdi, for FTDI support
### hidapi-libusb, for CMSIS-DAP support
## Compiling on windows
You can crosscompile blackmagic for windows with mingw or on windows
with cygwin. For compilation, headers for libftdi1 and libusb-1.0 are
needed. For running, libftdi1.dll and libusb-1.0.dll are needed and
the executable must be able to find them. Mingw on cygwin does not provide
a libftdi package yet.
To prepare libusb access to the ftdi device, run zadig https://zadig.akeo.ie/.
Choose WinUSB(libusb-1.0) for the BMP Ftdi device.
Running cygwin/blackmagic in a cygwin console, the program does not react
on ^C. In another console, run "ps ax" to find the WINPID of the process
and then "taskkill /F ?PID (WINPID)".
## Supported debuggers
REMOTE_BMP is a "normal" BMP usb connected
| Debugger | Speed | Remarks
| ------------ | ----- | ------
| REMOTE_BMP | +++ | Requires recent firmware for decent speed
| ST-Link V3 | ++++ | Requires recent firmware, Only STM32 devices supported!
| ST-Link V2 | +++ | Requires recent firmware, No CDCACM uart! Cortex only!
| ST-Link V2/1 | +++ | Requires recent firmware, Cortex only!
| CMSIS-DAP | +++ | Speed varies with MCU implementing CMSIS-DAP
| FTDI MPSSE | ++ | Requires a device descrition
| JLINK | - | Usefull to add BMP support for MCUs with built-in JLINK
## Device matching
As other USB dongles already connected to the host PC may use FTDI chips,
cable descriptions are provided to match with the dongle.
To match the dongle, at least USB VID/PID that must match.
If a description is given, the USB device must provide that string. If a
serial number string is given on the command line, that number must match
with serial number in the USB descriptor of the device.
## FTDI connection possibilities:
| Direct Connection |
| ----------------------|
| MPSSE_SK --> JTAG_TCK |
| MPSSE_DO --> JTAG_TDI |
| MPSSE_DI <-- JTAG_TDO |
| MPSSE_CS <-> JTAG_TMS |
\+ JTAG and bitbanging SWD is possible<br>
\- No level translation, no buffering, no isolation<br>
Example: [Flossjtag](https://randomprojects.org/wiki/Floss-JTAG).
| Resistor SWD |
|------------------------|
| MPSSE_SK ---> JTAG_TCK |
| MPSSE_DO -R-> JTAG_TMS |
| MPSSE_DI <--- JTAG_TMS |
BMP would allow direct MPSSE_DO ->JTAG_TMS connections as BMP tristates DO
when reading. Resistor defeats contentions anyways. R is typical choosen
in the range of 470R
\+ MPSSE SWD possible<br>
\- No Jtag, no level translation, no buffering, no isolation<br>
|Direct buffered Connection|
|--------------------------|
| MPSSE_SK -B-> JTAG_TCK |
| MPSSE_DO -B-> JTAG_TDI |
| MPSSE_DI <-B- JTAG_TDO |
| MPSSE_CS -B-> JTAG_TMS |
\+ Only Jtag, buffered, possible level translation and isolation<br>
\- No SWD<br>
Example: [Turtelizer]http://www.ethernut.de/en/hardware/turtelizer/index.html)
[schematics](http://www.ethernut.de/pdf/turtelizer20c-schematic.pdf)
The 'r' command line arguments allows to specify an external SWD
resistor connection added to some existing cable. Jtag is not possible
together with the 'r' argument.
### Many variants possible
As the FTDI has more pins, these pins may be used to control
enables of buffers and multiplexer selection in many variants.
### Reset, Target voltage readback etc
The additional pins may also control Reset functionality, provide
information if target voltage is applied. etc.
### Cable descriptions
Please help to verify the cable description and give feedback on the
cables already listed and propose other cable. A link to the schematics
is welcome.
## Feedback
### Issues and Pull request on https://github.com/blacksphere/blackmagic/
### Discussions on Discord.
You can find the Discord link here: https://1bitsquared.com/pages/chat
### Blackmagic mailing list http://sourceforge.net/mail/?group_id=407419
## Known deficiencies
### For REMOTE_BMP
#### On windows, the device node must be given on the command line
Finding the device from USB VID/PID/Serial in not yet implemented
### FTDI MPSSE
#### No auto detection
Cable description must be given on the command line