signal bandwidth preventing transmission

[codebreaker133]

I am testing with two adafruit rp2040 feathers with the rfm95 and every time I try to specify what bandwidth I would like to use ( tried all of them listed in the data sheet with various SF and CR respectively) I cant get a transition to go through even when there right next to each other, but when I comment out that line everything works fine. I will attach the transmitter and recover code bellow. I also have issues using any SF past 9 and from what I read the RFM95 should be capable of up to 12 but maybe I'm doing soothing wrong

====================================================
NODE 1;

# SPDX-FileCopyrightText: 2021 ladyada for Adafruit Industries
# SPDX-License-Identifier: MIT

# Example to send a packet periodically between addressed nodes with ACK
# Author: Jerry Needell
#
import time
import board # type: ignore
import busio # type: ignore
import digitalio # type: ignore
# import adafruit_rfm9x #type: ignore
# set the time interval (seconds) for sending packets
transmit_interval = 2.0

# Define radio parameters.
RADIO_FREQ_MHZ = 915.0  # Frequency of the radio in Mhz. Must match your
# module! Can be a value like 915.0, 433.0, etc.

# Define pins connected to the chip.
# set GPIO pins as necessary -- this example is for Raspberry Pi
CS = digitalio.DigitalInOut(board.RFM_CS)
RESET = digitalio.DigitalInOut(board.RFM_RST)
from adafruit_rfm import rfm9x
# Initialize SPI bus.
spi = busio.SPI(board.SCK, MOSI=board.MOSI, MISO=board.MISO)
# Initialze RFM radio
radio = rfm9x.RFM9x(spi, CS, RESET, RADIO_FREQ_MHZ)

# set delay before sending ACK
radio.ack_delay = 0.2
radio.enable_crc = True
radio.coding_rate = 4
# radio.signal_bandwidth = 62.5
radio.spreading_factor = 9
# set node addresses
radio.node = 1
radio.destination = 2
# initialize counter
counter = 0
ack_failed_counter = 0
radio.tx_power=23
import neoblink
# send startup message from my_node
neoblink.blink_neo_color(0, 255, 0)
radio.send_with_ack(bytes("startup message from node {}".format(radio.node), "UTF-8"))

# Wait to receive packets.
print("Waiting for packets...")
# initialize flag and timer
time_now = time.monotonic()
while True:
    # Look for a new packet: only accept if addresses to my_node
    packet = radio.receive(with_header=True)
    # If no packet was received during the timeout then None is returned.
    if packet is not None:
        # Received a packet!
        # Print out the raw bytes of the packet:
        print("Received (raw header):", [hex(x) for x in packet[0:4]])
        print("Received (raw payload): {0}".format(packet[4:]))
        print("RSSI: {0}".format(radio.last_rssi))
        neoblink.blink_neo_color(255, 0, 255)
        # send reading after any packet received
    
    if time.monotonic() - time_now > transmit_interval:
        # reset timeer
        time_now = time.monotonic()
        counter += 1
        # send a  mesage to destination_node from my_node
        neoblink.blink_neo_color(0, 0, 255)
        if not radio.send(
            bytes("message from node node {}".format(radio.node), "UTF-8")
        ):
            print("transmiting")            
            neoblink.blink_neo_color(000, 000, 255)
    if radio.packet_sent() == True:
            neoblink.blink_neo_color(255, 0, 255)

======================================================

NODE 2;

# SPDX-FileCopyrightText: 2021 ladyada for Adafruit Industries
# SPDX-License-Identifier: MIT

# Example to receive addressed packed with ACK and send a response
# Author: Jerry Needell
#
import time
import board # type: ignore
import busio # type: ignore
import digitalio # type: ignore

# Define radio parameters.
RADIO_FREQ_MHZ = 915.0  # Frequency of the radio in Mhz. Must match your
# module! Can be a value like 915.0, 433.0, etc.

# Define pins connected to the chip.
# set GPIO pins as necessary - this example is for Raspberry Pi
CS = digitalio.DigitalInOut(board.RFM_CS)
RESET = digitalio.DigitalInOut(board.RFM_RST)

# Initialize SPI bus.
spi = busio.SPI(board.SCK, MOSI=board.MOSI, MISO=board.MISO)
# Initialze RFM radio
from adafruit_rfm import rfm9x
radio = rfm9x.RFM9x(spi, CS, RESET, RADIO_FREQ_MHZ)

# set delay before transmitting ACK (seconds)
radio.ack_delay = 0.2
radio.enable_crc = True
radio.coding_rate = 4
# radio.signal_bandwidth = 62.5
radio.spreading_factor = 9
# set node addresses
radio.node = 2
radio.destination = 1
# initialize counter
counter = 0
ack_failed_counter = 0
radio.tx_power=23
import neoblink
neoblink.blink_neo_color(0, 255, 0)
# Wait to receive packets.
print("Waiting for packets...")
while True:
    # Look for a new packet: only accept if addresses to my_node
    packet = radio.receive(with_header=True)
    # If no packet was received during the timeout then None is returned.
    if packet is not None:
        neoblink.blink_neo_color(255, 255, 255)
        # Received a packet!
        # Print out the raw bytes of the packet:
        print("Received (raw header):", [hex(x) for x in packet[0:4]])
        print("Received (raw payload): {0}".format(packet[4:]))
        print("RSSI: {0}".format(radio.last_rssi))
        # send response 2 sec after any packet received
        time.sleep(2)
        counter += 1
        # send a  mesage to destination_node from my_node
        if not radio.send(
            bytes("response from node {} {}".format(radio.node, counter), "UTF-8")
        ):
            ack_failed_counter += 1
            print(" No Ack: ", counter, ack_failed_counter)

=====================================================

[jerryneedell]

For the bandwidth your commented out code uses KHz for the value -- It should be Hz

rfm.signal_bandwidth = 62500

Also - the coding rate should be 5,6,7 or 8 --- 4 is not valid.
Edited to add: when you set it to 4 -- the code actually sets it to 5...

Perhaps some better value checking is needed in the code. I'll look into that.

Take a look at the examples:
rfm_lora_sf_base.py
https://github.com/adafruit/Adafruit_CircuitPython_RFM/blob/main/examples/rfm_lora_sf_base.py
rfm_lora_sf_node.py
https://github.com/adafruit/Adafruit_CircuitPython_RFM/blob/main/examples/rfm_lora_sf_node.py

These should work for setting the SF to any value. And they have a commented out line for setting the Bandwidth.
Edited to add: For the higher SF settings - you have to adjust the setting for radio.receive_timeout -- try setting it to 2 seconds.

In your Node 2 code, you are testing for an "ACK" response from the send() but you need to use send_with_ack and receive_with_ack() for that to work,
I suggest getting it working with the plain send/receive first before adding in the _with_ack options.
the standard send() returns False if the transmission times_out (this should never happen)

I hope that helps.

[codebreaker133]

thanks for the tips, I have all the basics working now, definitely should have done some more rtfm'ing before posting an issue, is there a better place to post questions so as not to fill up this GitHub repo with questions, like a discord or forum, I know Adafruit has there main forum for project help would that be the best place to go?

[jerryneedell]

Excellent! I am glad you got it working. In general, it is best to file a Github issue if you think you have found a bug or if you want to suggest some improvement to the library.

You can use the Adafruit Support Forums https://forums.adafruit.com/index.php . This would be where you should post if you want "official support" from Adafruit. You also may get help from community members there as well.

I highly recommend joining the Adafruit Discord http://adafru.it/discord -- You can always post questions in the #help-with-radio channel if your question is specific to the using the radio boards. More general questions can go in #help-with-circuitpython or #help-with-projects There is a large and very helpful community on the Discord site that can provide a lot of help. It is also a great place to see what other people are doing.

The main thing is to keep asking questions if something is not working as you think it should. Someone else may be having or have had the same issue. Don't be shy about opening issue here if you think there is problem with the library or documentation.