Time to write an update about the RNet Wireless Stack. The stack has been successfully used for the Sumo Robots as wireless controller. In the last week, there has been a lot smaller and larger extensions for it. And because the nRF24L01+ modules are so inexpensive, I bunkered more than 50, with 20 still left to be deployed:

nRF24L01+ Transceiver Modules

With that many network nodes, it is good to have a small and scalable wireless stack. And as I have developed my own open source one, the stack grows with my needs :-).

Dynamic Payload (DPL)

One big difference between the Nordic Semiconductor nRF24L01 (without the +) and the nRF24L01+ is that the ‘+’ version supports DPL (Dynamic Payload). The Radio.c transeiver features a  macro

<br />#define NRF24_DYNAMIC_PAYLOAD  1 /* if set to one, use dynamic payload size */<br />
to enable/disable DPL:
<br />#if NRF24_DYNAMIC_PAYLOAD<br /><%%KEEPWHITESPACE%%>  /* enable dynamic payload */<br /><%%KEEPWHITESPACE%%>  RF1_WriteFeature(RF1_FEATURE_EN_DPL|RF1_FEATURE_EN_ACK_PAY|RF1_FEATURE_EN_DYN_PAY); /* set EN_DPL for dynamic payload */<br /><%%KEEPWHITESPACE%%>  RF1_EnableDynanicPayloadLength(RF1_DYNPD_DPL_P0); /* set DYNPD register for dynamic payload for pipe0 */<br />#else<br /><%%KEEPWHITESPACE%%>  RF1_SetStaticPipePayload(0, RPHY_PAYLOAD_SIZE); /* static number of payload bytes we want to send and receive */<br />#endif<br />
With DPL enabled, shorter data packets can be transmitted faster, plus the stack allows one more byte available as application payload.
RNet Stack Configuration
To configure the stack, there is now a configuration header file at the application level and ot overwrite default values inside the stack. Things like (short) address size, application message types, maximum payload size or acknowledge handling.
<br />/**<br />* \file<br />* \brief This is a configuration file for the RNet stack<br />* \author (c) 2013 Erich Styger, https://mcuoneclipse.com/<br />* \note MIT License (http://opensource.org/licenses/mit-license.html)<br />*<br />* Here the stack can be configured using macros.<br />*/<br /><br />#ifndef __RNET_APP_CONFIG__<br />#define __RNET_APP_CONFIG__<br /><br />#include "Platform.h"<br />#if PL_HAS_RADIO<br /><br />/*! Type ID's for application messages */<br />typedef enum {<br /><%%KEEPWHITESPACE%%>  RAPP_MSG_TYPE_STDIN = 0x00,<br /><%%KEEPWHITESPACE%%>  RAPP_MSG_TYPE_STDOUT = 0x01,<br /><%%KEEPWHITESPACE%%>  RAPP_MSG_TYPE_STDERR = 0x02,<br /><%%KEEPWHITESPACE%%>  RAPP_MSG_TYPE_DATA = 0x03<br />} RAPP_MSG_Type;<br /><br />#define RNET_CONFIG_TRANSCEIVER_PAYLOAD_SIZE  32<br /><%%KEEPWHITESPACE%%>  /*!< Size of the physical transceiver payload (bytes), max 32 bytes for nRF24L01+, max 128 bytes for MC1320x */<br /><br />#define RNET_CONFIG_SHORT_ADDR_SIZE   1<br /><%%KEEPWHITESPACE%%>  /*!< size of short address type. Either 1 or 2 */<br /><br />#define RNET_CONFIG_USE_ACK           1<br /><%%KEEPWHITESPACE%%>  /*!< If set to 1, the NWK layer will send an acknowledge message for every data packet received */<br /><br />#endif /* PL_HAS_RADIO */<br /><br />#endif /* __RNET_APP_CONFIG__ */<br />
RNet Acknowledge
The Rnet stack uses internally flags for things like acknowledge handling on the wireless stack level. As such, it is possible now to send messages either with or without acknowledge. If the application wants an ACK, then it passes RPHY_PACKET_FLAGS_REQ_ACK:
<br />if (RAPP_SendPayloadDataBlock(&val8, sizeof(val8), RAPP_MSG_TYPE_DATA, APP_dstAddr, RPHY_PACKET_FLAGS_REQ_ACK) != ERR_OK) {<br />CLS1_SendStr((unsigned char*)"ERR: failed sending data\r\n", io->stdErr);<br />return ERR_FAILED;<br />}<br />
nRF24L01+ Processor Expert Component
The component has been extended with several functions:
nRF24L01+ Component

Functions to enable and deal with DPL (Dynamic PayLoad)
Functions to read/write the FEATURE register (dynamic payload and acknowledge control)
Function to read the OBSERVE_TX register: that way I can get the number of retry and number of re-transmitted packets.
Function to read the RPD (Received Power Detector) bit.

❗ I have found that the RPD information often reports a zero bit. This because it easily gets reset by a ‘foreign’ packet, e.g. having WiFi traffic. With this, the usage of that bit is somewhat minimal.
Shell Support
The Command Line Shell support has been extended: It is now possible to change the radio channel from the command line. The radio channel along with state machine state and the information from the OBSERVE_TX register is displayed in the shell too:
Radio Status in Shell
The optional built-in Sniffing support reports extended information about every incoming or outgoing packet:
Sniffing Output
That packet sniffing has helped me many times as debugging aid and to quickly see what is going on.
Sources on GitHub
The sources and example project for FRDM-KL25Z are as always available on GitHub. The stack sources itself are available here.
Summary
I’m using the stack now in multiple projects taking advantage of wireless communication, both with the Nordic Semiconductor nRF24L01+ and the Freescale MC1320x/MC1321x transceiver. I have experimental short address assignment based on the Kinetis UID working, but this is still work in progress.
Happy RNeting 🙂

		
	
			

			
			
Share this:
Print
Email
Twitter
Facebook
LinkedIn
Tumblr
Pinterest
Pocket
WhatsApp
Telegram
Like Loading...


	
Related