From the schematics, we see that there are three pins associated with the USB port. 1. PA11 2. PA12 3. PD2
The Pins PA11 and PA12 are PA11 – USB D- PA12 – USB D+
These two pins will be configured by the stm32cube ide when you enable the USB device.
PD2 should be configured as GPIO pin. Because the USB FS implementation says to pull up the D+ line to 3.3V. The pull up is performed by the S8550 PNP transistor. So by making the PD2 pin LOW, we enable the USB FS, since it makes the D+ pull up.
We also need to select the Communication Device Class as Class For FS IP.
After configuring the cube mx project. we can proceed to generate code.
The code needs to add the following header file
/* USER CODE BEGIN Includes */
#include "usbd_cdc_if.h"
#include "string.h"
/* USER CODE END Includes */
and then in the main() function. you can write this code in while loop
/* USER CODE BEGIN 2 */
HAL_GPIO_WritePin(GPIOD, GPIO_PIN_2, GPIO_PIN_RESET);
/* USER CODE END 2 */
/* USER CODE BEGIN WHILE */
uint8_t *data = "Hello World from USB CDC\r\n";
while (1)
{
CDC_Transmit_FS(data, strlen(data));
HAL_Delay (1000);
/* USER CODE END WHILE */
/* USER CODE BEGIN 3 */
}
/* USER CODE END 3 */
After uploading the code to your microcontroller. It will be displayed in your windows device manager as “USB Serial Device”.
You can Connect to the Com port using the serial terminal software such as YAT, Putty or CoolTerm etc. Note: Since it is a virtual com port, you dont have to set a specific baud rate.
To program the AVR microcontroller you use “avrdude” to flash the hex files in the microcontroller. avrdude is a command line tool. Every time you have to flash the microcontroller with a new file you have to write the command. This AVRHexFlashGUI uses the avrdude software to flash the microcontroller but it provides a Graphical User Interface.
There is a special feature I have implemented which is “QuickSet” Toolbar which has a “Quick FLASH” button. This toolbar floats on top of the screen. And provides an easy-to-use button for flashing the firmware files. It has an indicator that turns it’s color to green if the programming is successful or turns red if the programming is unsuccessful. It also has an ‘X’ button to switch off this toolbar. Software such as microchip mplab x ide does not have an option to integrate the avrdude commands like in microchip studio(formerly Atmel Studio). This toolbar provides an easy access to flashing. You do not have to do anything else. Just launch the program and enable the QuickSet toolbar.
AVR microcontrollers are widely used in embedded systems development due to their versatility and ease of programming and also their low cost. Flashing firmware or code onto these microcontrollers is a fundamental task during development. The AVRHexFlashGUI is a graphical user interface (GUI) application built using the Tkinter library in Python.
The AVRHexFlashGUI application streamlines the process of flashing firmware onto AVR microcontrollers using a user-friendly interface. It offers the following features:
Microcontroller Selection: The application allows users to select the target microcontroller from a list of supported devices.
Programmer Configuration: Users can specify the programmer to be used for flashing the firmware. This information is crucial for establishing a connection between the computer and the microcontroller.
HEX File Selection: Users can browse their computer for the HEX file containing the firmware they want to flash onto the microcontroller.
Quick Flash: The application provides a quick flash button that initiates the flashing process using the selected programmer, microcontroller, and HEX file.
Read the Microcontroller Flash Memory: The user can read the unprotected flash memory and save it in the program folder as “HexFromDevice.hex”
AVR Fuse Settings: The application offers the ability to read and display the current fuse settings of the connected AVR microcontroller. Users can also write new fuse settings if needed.
Output Display: The application displays the output of the avrdude tool, which is responsible for flashing the firmware and handling the communication with the microcontroller.
Usage
To use the AVRHexFlashGUI application, follow these steps:
Launch the application.
Select the target microcontroller.
Specify the programmer to be used for flashing.
Load the desired HEX file by clicking the “Browse” button.
Click the “Program AVR” button to start the flashing process.
Monitor the avrdude output to ensure successful flashing.
Optionally, use the “Fuse Setting” section to read, modify, and write fuse settings.
AVRHexFlash Quick Flash Toolbar with MPLAB X IDE
Conclusion
The AVRHexFlashGUI application simplifies the process of flashing firmware onto AVR microcontrollers by providing an intuitive and user-friendly interface. With features for microcontroller selection, programmer configuration, HEX file loading, and fuse settings, developers can efficiently program their microcontrollers. The use of Tkinter and Python makes it easy to create and customize the GUI, enhancing the overall user experience. This application is a valuable tool for both beginners and experienced developers working with AVR microcontrollers. By streamlining the flashing process, it helps save time and ensures accurate firmware deployment.
This is a very simple demonstration of the Unsecured Bluetooth Low Energy technology.
I am using two Raspberry Pi Pico W for this. One will be operated in Central Role and the other will be in the Peripheral Role.
The peripheral device will advertise the temperature data of the rp2040 chip.
The Central device will scan the surrounding and connect to the peripheral device to receive the temperature data. The central device does not use any passcode or pairing methods to connect to the peripheral device.
# This example finds and connects to a peripheral running the
# UART service (e.g. ble_simple_peripheral.py).
import bluetooth
import random
import struct
import time
import micropython
from ble_advertising import decode_services, decode_name
from micropython import const
_IRQ_CENTRAL_CONNECT = const(1)
_IRQ_CENTRAL_DISCONNECT = const(2)
_IRQ_GATTS_WRITE = const(3)
_IRQ_GATTS_READ_REQUEST = const(4)
_IRQ_SCAN_RESULT = const(5)
_IRQ_SCAN_DONE = const(6)
_IRQ_PERIPHERAL_CONNECT = const(7)
_IRQ_PERIPHERAL_DISCONNECT = const(8)
_IRQ_GATTC_SERVICE_RESULT = const(9)
_IRQ_GATTC_SERVICE_DONE = const(10)
_IRQ_GATTC_CHARACTERISTIC_RESULT = const(11)
_IRQ_GATTC_CHARACTERISTIC_DONE = const(12)
_IRQ_GATTC_DESCRIPTOR_RESULT = const(13)
_IRQ_GATTC_DESCRIPTOR_DONE = const(14)
_IRQ_GATTC_READ_RESULT = const(15)
_IRQ_GATTC_READ_DONE = const(16)
_IRQ_GATTC_WRITE_DONE = const(17)
_IRQ_GATTC_NOTIFY = const(18)
_IRQ_GATTC_INDICATE = const(19)
_ADV_IND = const(0x00)
_ADV_DIRECT_IND = const(0x01)
_ADV_SCAN_IND = const(0x02)
_ADV_NONCONN_IND = const(0x03)
_UART_SERVICE_UUID = bluetooth.UUID("6E400001-B5A3-F393-E0A9-E50E24DCCA9E")
_UART_RX_CHAR_UUID = bluetooth.UUID("6E400002-B5A3-F393-E0A9-E50E24DCCA9E")
_UART_TX_CHAR_UUID = bluetooth.UUID("6E400003-B5A3-F393-E0A9-E50E24DCCA9E")
class BLESimpleCentral:
def __init__(self, ble):
self._ble = ble
self._ble.active(True)
self._ble.irq(self._irq)
self._reset()
def _reset(self):
# Cached name and address from a successful scan.
self._name = None
self._addr_type = None
self._addr = None
# Callbacks for completion of various operations.
# These reset back to None after being invoked.
self._scan_callback = None
self._conn_callback = None
self._read_callback = None
# Persistent callback for when new data is notified from the device.
self._notify_callback = None
# Connected device.
self._conn_handle = None
self._start_handle = None
self._end_handle = None
self._tx_handle = None
self._rx_handle = None
def _irq(self, event, data):
if event == _IRQ_SCAN_RESULT:
addr_type, addr, adv_type, rssi, adv_data = data
if adv_type in (_ADV_IND, _ADV_DIRECT_IND) and _UART_SERVICE_UUID in decode_services(
adv_data
):
# Found a potential device, remember it and stop scanning.
self._addr_type = addr_type
self._addr = bytes(
addr
) # Note: addr buffer is owned by caller so need to copy it.
self._name = decode_name(adv_data) or "?"
self._ble.gap_scan(None)
elif event == _IRQ_SCAN_DONE:
if self._scan_callback:
if self._addr:
# Found a device during the scan (and the scan was explicitly stopped).
self._scan_callback(self._addr_type, self._addr, self._name)
self._scan_callback = None
else:
# Scan timed out.
self._scan_callback(None, None, None)
elif event == _IRQ_PERIPHERAL_CONNECT:
# Connect successful.
conn_handle, addr_type, addr = data
if addr_type == self._addr_type and addr == self._addr:
self._conn_handle = conn_handle
self._ble.gattc_discover_services(self._conn_handle)
elif event == _IRQ_PERIPHERAL_DISCONNECT:
# Disconnect (either initiated by us or the remote end).
conn_handle, _, _ = data
if conn_handle == self._conn_handle:
# If it was initiated by us, it'll already be reset.
self._reset()
elif event == _IRQ_GATTC_SERVICE_RESULT:
# Connected device returned a service.
conn_handle, start_handle, end_handle, uuid = data
print("service", data)
if conn_handle == self._conn_handle and uuid == _UART_SERVICE_UUID:
self._start_handle, self._end_handle = start_handle, end_handle
elif event == _IRQ_GATTC_SERVICE_DONE:
# Service query complete.
if self._start_handle and self._end_handle:
self._ble.gattc_discover_characteristics(
self._conn_handle, self._start_handle, self._end_handle
)
else:
print("Failed to find uart service.")
elif event == _IRQ_GATTC_CHARACTERISTIC_RESULT:
# Connected device returned a characteristic.
conn_handle, def_handle, value_handle, properties, uuid = data
if conn_handle == self._conn_handle and uuid == _UART_RX_CHAR_UUID:
self._rx_handle = value_handle
if conn_handle == self._conn_handle and uuid == _UART_TX_CHAR_UUID:
self._tx_handle = value_handle
elif event == _IRQ_GATTC_CHARACTERISTIC_DONE:
# Characteristic query complete.
if self._tx_handle is not None and self._rx_handle is not None:
# We've finished connecting and discovering device, fire the connect callback.
if self._conn_callback:
self._conn_callback()
else:
print("Failed to find uart rx characteristic.")
elif event == _IRQ_GATTC_WRITE_DONE:
conn_handle, value_handle, status = data
print("TX complete")
elif event == _IRQ_GATTC_NOTIFY:
conn_handle, value_handle, notify_data = data
if conn_handle == self._conn_handle and value_handle == self._tx_handle:
if self._notify_callback:
self._notify_callback(notify_data)
# Returns true if we've successfully connected and discovered characteristics.
def is_connected(self):
return (
self._conn_handle is not None
and self._tx_handle is not None
and self._rx_handle is not None
)
# Find a device advertising the environmental sensor service.
def scan(self, callback=None):
self._addr_type = None
self._addr = None
self._scan_callback = callback
self._ble.gap_scan(2000, 30000, 30000)
# Connect to the specified device (otherwise use cached address from a scan).
def connect(self, addr_type=None, addr=None, callback=None):
self._addr_type = addr_type or self._addr_type
self._addr = addr or self._addr
self._conn_callback = callback
if self._addr_type is None or self._addr is None:
return False
self._ble.gap_connect(self._addr_type, self._addr)
return True
# Disconnect from current device.
def disconnect(self):
if self._conn_handle is None:
return
self._ble.gap_disconnect(self._conn_handle)
self._reset()
# Send data over the UART
def write(self, v, response=False):
if not self.is_connected():
return
self._ble.gattc_write(self._conn_handle, self._rx_handle, v, 1 if response else 0)
# Set handler for when data is received over the UART.
def on_notify(self, callback):
self._notify_callback = callback
def demo():
not_found = False
def on_scan(addr_type, addr, name):
if addr_type is not None:
print("Found peripheral:", addr_type, addr, name)
central.connect()
else:
nonlocal not_found
not_found = True
print("No peripheral found.")
central.scan(callback=on_scan)
# Wait for connection...
while not central.is_connected():
time.sleep_ms(100)
if not_found:
return
print("Connected")
def on_rx(v):
buf1 = bytearray(v)
print("RX ")
for _ in v:
print(chr(_), end='')
print("")
central.on_notify(on_rx)
#with_response = False
with_response = True
i = 0
while central.is_connected():
try:
v = str(i) + "_"
print("TX", v)
central.write(v, with_response)
except:
print("TX failed")
i += 1
time.sleep_ms(2000 if with_response else 30)
print("Disconnected")
if __name__ == "__main__":
ble = bluetooth.BLE()
central = BLESimpleCentral(ble)
while(1):
demo()
ble_Peripheral_device.py
# This example demonstrates a UART periperhal.
import bluetooth
import random
import struct
import time
from ble_advertising import advertising_payload
from micropython import const
def Temp_sensor():
# Configure the internal temperature sensor
sensor_temp = machine.ADC(machine.ADC.CORE_TEMP)
conversion_factor = 3.3 / 65535
raw_temp = sensor_temp.read_u16() * conversion_factor
temperature = (27 - (raw_temp - 0.706) / 0.001721)
return temperature
_IRQ_CENTRAL_CONNECT = const(1)
_IRQ_CENTRAL_DISCONNECT = const(2)
_IRQ_GATTS_WRITE = const(3)
_FLAG_READ = const(0x0002)
_FLAG_WRITE_NO_RESPONSE = const(0x0004)
_FLAG_WRITE = const(0x0008)
_FLAG_NOTIFY = const(0x0010)
_UART_UUID = bluetooth.UUID("6E400001-B5A3-F393-E0A9-E50E24DCCA9E")
_UART_TX = (
bluetooth.UUID("6E400003-B5A3-F393-E0A9-E50E24DCCA9E"),
_FLAG_READ | _FLAG_NOTIFY,
)
_UART_RX = (
bluetooth.UUID("6E400002-B5A3-F393-E0A9-E50E24DCCA9E"),
_FLAG_WRITE | _FLAG_WRITE_NO_RESPONSE,
)
_UART_SERVICE = (
_UART_UUID,
(_UART_TX, _UART_RX),
)
class BLESimplePeripheral:
def __init__(self, ble, name="mpy-uart"):
self._ble = ble
self._ble.active(True)
self._ble.irq(self._irq)
((self._handle_tx, self._handle_rx),) = self._ble.gatts_register_services((_UART_SERVICE,))
self._connections = set()
self._write_callback = None
self._payload = advertising_payload(name=name, services=[_UART_UUID])
self._advertise()
def _irq(self, event, data):
# Track connections so we can send notifications.
if event == _IRQ_CENTRAL_CONNECT:
conn_handle, _, _ = data
print("New connection", conn_handle)
self._connections.add(conn_handle)
elif event == _IRQ_CENTRAL_DISCONNECT:
conn_handle, _, _ = data
print("Disconnected", conn_handle)
self._connections.remove(conn_handle)
# Start advertising again to allow a new connection.
self._advertise()
elif event == _IRQ_GATTS_WRITE:
conn_handle, value_handle = data
value = self._ble.gatts_read(value_handle)
if value_handle == self._handle_rx and self._write_callback:
self._write_callback(value)
def send(self, data):
for conn_handle in self._connections:
self._ble.gatts_notify(conn_handle, self._handle_tx, data)
def is_connected(self):
return len(self._connections) > 0
def _advertise(self, interval_us=500000):
print("Starting advertising")
self._ble.gap_advertise(interval_us, adv_data=self._payload)
def on_write(self, callback):
self._write_callback = callback
def demo():
ble = bluetooth.BLE()
p = BLESimplePeripheral(ble)
def on_rx(v):
print("RX", v)
p.on_write(on_rx)
i = 0
while True:
if p.is_connected():
# Short burst of queued notifications.
transmit_msg = "Temperature: "+str(Temp_sensor())
p.send(str(transmit_msg))
'''
for _ in range(3):
data = "oz"+ str(i) + "_"
print("TX", data)
p.send(data)
i += 1
'''
i = i + 1
time.sleep_ms(1000)
if __name__ == "__main__":
demo()
