Hi All,
I am trying to achieve the downlink on Chirpstack for some time. But no success so far. I was able to get the downlink done in short period of time on TTN. But not able to achieve it on the chirpstack. Its difficult to find the clear guidance for downlink on chirpstack. I would like to share the steps I have done here to cross check my procedure, configuration and fix the downlink issue.
Settup details
Frequency Band : EU868
Node hardware : Arduino Uno
Library : LMIC
Gateway : RAK 2245
Lorawan server : RAK test server
Node program :
Using the default ttn-abp program from lmic, here
Program uses EU868 band
Using LMIC.dn2Dr = DR_SF12; for chirpstack and LMIC.dn2Dr = DR_SF9; for TTN.
Confirmed with TTN. I can able to get downlink data on the node side.
There is no other changes on the ttn-abp.ino side
Gateway
Using RAK’s Gateway OS as it is and configured the lorawan server with external chirpstack server given by RAK.
– Done the gateway ID setup on the global_conf.json
– No other changes on global_conf.json file. Tx_enable: false in radio_1 and frequency is 868500000
On the Chirpstack side
– Existing service profile used. Nothing changed.
– Existing device profile used
– Class A with ABP, RX1 Delay : 5, RX1 Data rate off-set : 0, RX2 Datarate : 0, RX2 Chennal frequency : 869525000 & factory preset frequency : 868100000, 868300000, 868500000, 867100000, 867300000, 867500000, 867700000, 867900000 (No idea what should I use).
– Class B / C Disabled
– Application created
– Device created and Device address, Network session key & Application session key added on the ttn-abp.ino progam.
Output
Uplink::
- The sample hello world received on the server side as uplink data sent by node.
- The log confirms the data transfers on the gateway side by using, tcpdump -AUq port 1700
- So far is working fine
Downlink ::
– Create a downlink queue from Device window. Gave, Port : 4, Confirmed Downlink enabled and give “aGk=” as base64 encoded data.
– The given downlink queue listed. The gateway receives the downlink frames after the uplink is done on the node side. The txpk confirm the data transfer from server to gateway.
– Recevied an “ack” frame once the downlink queue is clear. It contains as follows,
applicationID:“21”
applicationName:“app”
deviceName:“test2”
devEUI:“af9df28984d0b71a”
acknowledged:false
fCnt:73
tags:
The gateway log is,
.{“txpk”:{“imme”:true,“rfch”:0,“powe”:27,“ant”:0,“brd”:0,“freq”:869.525,“modu”:“LORA”,“datr”:“SF12BW125”,“codr”:“4/5”,“ipol”:true,“size”:22,“data”:“oB4F6QGHSQADAAcAAQgBBM9sLGaltg==”}} 17:14:01.128266 IP rak-gateway.58644 > 209.250.251.9.vultr.com.1700: UDP, length 12
No data is received on the node side. Any kind of input is appreciated to achieve the downlink on EU868.
TIA