When connecting a Black Magic Probe to my mac i'm not able to receive any data when connecting UART RX to UART TX. I tried updating the firmware to the latest version without success.
I tried multiple Black Magic probes, both on Mac and Windows without success. The UART TX led on the board blinks when transmitting. I verified the connection was to the correct device endpoint (second interface of the device). When using an oscilloscoop I did not see and data transmitted on the TX output port.
By default the Black Magic Probe does not power the target. The Black Magic Probe uses levels shifters that require a reference voltage provided by the target to be present. Without this reference level the levels shifter buffer will not output any signals or receive any signals.
It is possible to use the 3.3V LDO on the Black Magic Probe as a reference by using this command in GDB: "monitor tpwr enable". Use the command: "monitor tpwr" to validate the target is powered by the Black Magic Probe. Please be careful the target supports 3.3V power and the total power consumption is limited. By supplying the power to the target the level shifters have a reference level and a UART loopback should work by connecting the RX and TX pin.
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I am trying to flash code over CANBUS on Nucleo-F446. I am referring this application notes
https://www.st.com/resource/en/application_note/cd00264321-can-protocol-used-in-the-stm32-bootloader-stmicroelectronics.pdf
So according to it in Boot mode the default baud rate of CAN is 125KBPS and we need to use PB5 and PB13 pin which are CAN2 pins.
For testing I tried to send CAN message with DLC=0 and STDID = 0x79 for which STM32 should return a ACK with same ID i.e. 0x79.
But I am not getting any response.
You must add a external clock to your Nucleo Board
The system clock is derived from the embedded internal high-speed RC for USARTx and
I2Cx bootloaders. This internal clock is also used for CAN and DFU (USB FS Device) but
only for the selection phase. An external clock multiple of 1 MHz (between 4 and 26 MHz) is
required for CAN and DFU bootloader execution after the selection phase.
STM Bootloader Description
I have a third party device that is UART programmable.
I need to create a USB - UART bridge with a functional password (programming only after entering the correct password)
generated the code using the latest version of STM32CubeMX for Atollic TrueSTUDIO for STM32 9.3.0 ...
I transfer data between USB and UART through a buffer (one for usb-uart, and another one for uart-usb)
when I try to transfer several characters everything is OK, but when I try to transfer a large data packet, problems start due to the fact that the USB speed is much higher than the UART ...
there are two questions:
1.How do I tell USB that I need to stop transferring data and wait until the UART (buffer) is busy
2.How on the side of the microcontroller to get the baud rate set on the PC (set when the terminal is connected to the virtual COM port)
USB provides flow control. That's what you need to implement. A general introduction can be found here:
https://medium.com/#manuel.bl/usb-for-microcontrollers-part-4-handling-large-amounts-of-data-f577565c4c7d
Basically, the setup for the USB-to-UART direction should be:
Indicate that the code is ready to receive a USB packet
Receive a USB packet
Indicate that you are no longer ready to receive a USB packet
Transmit the data via UART
Start over
Step 0: Initial setup
Call USBD_CDC_SetRxBuffer to set the buffer for receiving the USB data. Unless you use several buffers to achieve higher throughput, a single call at the start of the program is sufficient.
Step 1: Ready to receive data
Call USBD_CDC_ReceivePacket. Other than what the name implies, this function indicates that the app is ready to receive data. It immediately returns before the data has actually been received.
Step 2: Receive a USB packet
You don't need to do anything here. It will happen automatically. Once it's complete, CDC_Itf_Receive will be called.
Step 3: Indicate that you are no longer ready to receive a USB packet
Nothing to do here. This happens automatically whenever a packet has been received (and double buffering is not enabled).
Step 4: Transmit the data via UART
I guess you know how to do this. It's up to you whether you want to do it in a blocking fashion or using DMA.
Since a callback is involved, you cannot put this code into the main loop. It might be possible to put all code into CDC_Itf_Receive if blocking UART is used. It would appear in the order 2, 3, 4, 1. Additionally, initialization is needed (0 and 1).
In the UART-to-USB direction, you would need to implement flow control on the UART. The USB flow control is managed by the host. Even though USB is much faster than UART, flow control is relevant as the application on the host can process data as slow as it likes to.
Regarding question 2: I'm not sure I understand it... The microcontroller cannot set the baud rate on the host. Either the host can specify a baud rate (transmitted over USB and applied to UART), or if the UART has a fixed baud rate, you can ignore baud rate (any baud rate set on the host side will work as it does not apply to USB).
MCU : STM32L496
JFlash version: v6.32i
We are facing the "Connection to target under reset failed" issue, when we try to program the board with STM32 MCU.
We were programming the board before with no issues. This error started appearing suddenly and now we are not able to program the board. When we scoped the reset pin of the MCU, the reset pin is going low when we click the connect button in the JFlash and clearly the board is resetting (We can see the firmware functionality restarting).
We tried the following:
Tied the BOOT0 pin to VDD and tried booting to the system memory and then tried programming. But this doesn't made any difference.
Tried always pulling down the reset pin to GND while trying to flash.
We have ensured that there are no issues with the track leading to the JTAG interface of the MCU.
Could you please help to resolve this situation?
Is there any possibility that the firmware currently running in the MCU could prevent the flashing and lock the device?
STM32L4 has a feature called Read-out Protection (RDP). See section 1.1 of AN4758. If your firmware application sets (intentionally or accidentally) the RDP level to 1 or 2 in the "option bytes" memory area then the SWD/JTAG port is disabled from accessing flash memory (read, write, and erase).
If the RDP is level 0 or 1 then you should be able to read the option byte memory area. If RDP is level 1 then you should be able to set it back to level 0. The flash memory will be erased when setting RDP back to level 0 but the SWD/JTAG port will get re-enabled. If the RDP level is 2 then I believe there is no way to reset it.
This is a common problem with STM32 SWD interface. For successful programming you should not power your custom board/ other hardware with the ST link power, instead you should make the GND connection common and supply from external source. And if you are using ST link only for programming and not for debugging then you should use the STM32 bootloader(easier).
I'm learning embedded development, and I'm trying to communicate with the accelerometer (LIS3DSH) on the discovery board using the SPI protocol. I'm only using CMSIS headers so that I'm forced to interact directly with the registers.
According to the schematics, these are the pins being used by the board for communication with the accelerometer:
PA5: SPI1_SCK
PA7: SPI1_MOSI
PA6: SPI1_MISO
PE3: CS_I2C/SPI
From my theoretical understanding of the SPI protocol, whenever I want to receive or transmit data between the master and the slave, I first need to pull the CS pin (PE3) down and then start the communication. This seems to be confirmed by the LIS3DSH user manual as well.
But now I'm confused about what the meaning of SSM is. According to the board's user manual, this is what the software slave management bit does:
When the SSM bit is set, the NSS pin input is replaced with the value from the SSI bit.
The NSS pin is nothing but the slave select pin, right? Which means it is PE3 in this case.
The SSI bit is bit 8 on the SPI_CR1 register. Does this mean I should instead toggle this SSI bit instead of PE3? That doesn't make sense because how would board know that the PE3 is the relevant CS pin?
So how are the CS pin/line and the SSM bit related, if at all?
If they're not related, do I need to configure the PE3 pin with alternate function mode and and as a pull-up, and then pull it low every time I need to communicate using SPI with the accelerometer?
The NSS pin is an input used as a CS by some other device when the SPI peripheral is in slave mode, or can be used as an output to support multi-master configurations.
If you are operating the SPI in single-master mode, the pin is not used at all.
Moreover SPI1_NSS is an alternate function of PA4 or PA15 so not related to the CS GPIO on PE3 in your case. In master mode, any number of available GPIO pins may be used as CS lines for each peripheral on the same SPI bus, and is driven in software - it is not an "alternate function", and not part of, or controlled by, the SPI peripheral.
I'm trying to interface the Mindwave (http://store.neurosky.com/products/mindwave-1) with my Altys board, through the USB UART port. The dongle I'm trying to connect is basically a wireless reciever that outputs serial data stream on the USB connection. I'm trying to read in this serial stream on the FPGA.
The problem I'm seeing is that when I try to Chipscope the UartRx pin (A16), I see no activity on it even though the dongle is supposed to send 0xAA in standby mode.
Since the FPGA does not power the dongle, I have it connected to an external power USB hub and then connect the hub to the FPGA. However I don't see any activity.
Do I need to convert the signals to another level, or invert them? I thought the EXAR chip takes care of it.
Did you try swapping RX and TX?
Did you have acces to a scope? To check you can repeatly send 'U's (0x55) and look with a scope to see which line is RX and which is TX. You can also check the speed of the interface with this method.