ZGUS radio library for eZ430-RRF3500 with simple radio modem source code app | MSP430

A snapshot ZGUS radio library, built on SimpliciTI, with a sample radio
modem source code application for the eZ430-RF2500 kit is available from
http://www.zgus.com/rf/zgusrf

The library is for Code Composer Essentials 3 development suite and
works with the free version of Code Composer Essentials 3.

The radio libraries package
(http://www.zgus.com/rf/zgusrf/radio_libraries.zip
) consists of two
compiled libraries (zgusrf/zgusrf.lib by ZGUS and
SimpliciTI/SimplicitTI.lib ported from TI code) and a small source code
radio modem application in relay_uart_rf/ that allows two UART ports to
communicate transparently by radio without any hardware or inbuilt
software handshaking. The UARTS do not have to run at the same BAUD
rates.

The radio modem library purpose is solely to enable demonstration of use
of a forthcoming application by radio in as simple and cheaply a manner
as practical. Since it is unlikely there will be further development and
documentation before use of the ZGUS radio modem library in its first
sample application, the library is being released now. The radio modem
library facilities and buffering capabilities have been designed to fit
specific applications and may not suit your applications. The fact is
the library works nicely for its intended purpose.

While support is only applicable for use in sample ZGUS applications,
anyone with questions arising from this posting is welcome to post them
to the ZGUS support forum at http://groups.yahoo.com/group/zgus
.

Following are some specific usage notes, including current limitations.

Currently the ZGUS uart and radio initialisation library call txrx_init
will only accept parameters for UART baud rates 2400 or 9600. These
parameters have nothing to do with the radio baud rates. To try other
UART baud rates then the UART baud rate will need to adjusted AFTER a
call to txrx_init. There are two other txrx_init parameters, one is the
SimpliciTI radio device address, the other is a timeout parameter in
milliseconds used for both radio and UART purposes. 100 is a safe value.

One side must call with rf_open(RFOPEN_NOBLOCK) for a SMPL_Link no
blocking call and the other side with rf_open(RFOPEN_BLOCK) for a
SMPL_LinkListen blocking call that is repeated until SMPL_SUCCESS
results. There is currently little use of power saving. To compile for
blocking use #define LINKLISTEN in zgus\__sgetapps.h (with //#define
LINKTO commented out). To compile for non blocking use #define LINKTO in
zgus\__sgetapps.h (with //#define LINKLISTEN commented out). These
macros automatically ensure different SimpliciTI radio device addresses
are used.

After txrx_init and rf_open, a call to relay_rf() (which does not
return) will implement transparent transfer of data between the UART and
radio in both directions.

On a practical usage note, the eZ430 MSP430 Application UART causes CPU
usage to jump very high after the first character has been sent, so it
is recommended to use another USB-UART device with a PC. The problem
occurred with both HyperTerm and with Hidprobe with the eZ430 MSP430
Application UART. The problem did not occur with HyperTerm or with
Hidprobe when the PC was connected to a FTDI chip instead (using a
DLP-2232M board) instead of the eZ430 Application UART.

Hidprobe PC software for UART use is available from
http://www.zgus.com/hid

The basic radio parameters are the same as for the port of
SimpliciTI-1.0.6 to Code Composer Essentials for the '2 simple End
Devices with bi-di' application for the ez430-RF2500 board. This port is
also available from http://www.zgus.com/rf in
source code form. To change hard coded radio register values then
facilities provided by the SimpliciTI library can be used. The compiled
library has a number of minor differences with the source code version.
The main one is that TimerA is kept running and overflows through
continuous counting without use of TACCR0.

A requirement of any application that uses zgusrf.lib is to implement a
timer tick that keeps a variable defined in the application as
volatile mstime_t mstime_isr=0;
updated.

This variable is declared as an extern in zgusrf.lib in order to force a
user to pay attention to its importance by causing an error if the
variable is not defined at the application level. However the user is
allowed the user to implement update of the variable whatever way they
choose. Please see txrx_sw.c in the application for an example. In fact
easy update of this variable is the reason for the modification to
SimplicTI so as TimerA is not stopped and overflows through continuous
counting. A function in zgusrf.lib that directly uses mstime_isr is
mstime_t mstime(void).

The ZGUS library buffers characters received from the UART to a size of
four times the size of the data payload transferred by radio (64 bytes).
The data payload per radio transferred is currently hard coded to 16
resulting in a hard coded MAX_APP_PAYLOAD that is set to 17. If
received UART characters have not been removed and placed in other
buffers in time then data to be transmitted will be overwritten by later
data from the UART. The ZGUS library requires all radio data packets to
be acknowledged. If there is a long run of failed acknowledgments then
a reset is forced automatically. There is currently no facility to
retransmit an unacknowledged packet.

Pumping data into the UART in bursts of no more than 63 bytes, rather
than with long gaps between characters sent, will result in more
efficient use of the radio channel.

The easiest way to test radio modem is to use the eZ430 Application UART
with one radio board (say non blocking open) and use the battery board
on the other radio board (say blocking open) and short P3.4 to P3.5 on
the battery board.

If the end opened as RFOPEN_BLOCK end loses power then after re-powering
the other end will reset after a number of consecutive failed
acknowledgments which will force a fresh link.

If the end opened as RFOPEN_NOBLOCK end loses power then after
re-powering communication will re-establish nearly immediately.

SimpliciTI.lib uses the PORT2 interrupt. Zgusrf.lib uses UART TX
interrupt and a UART RX interrupt to transfer buffered data. The sample
application use the TIMERA1 (overflow flag)interrupt to provide a
required timer tick

There are functions in the ZGUS radio library that are for other
applications and have no relevance for radio modem use.

The compiled SimpliciTI.lib hard codes smpl_nwk_config.dat (converted
for include file use) parameters to
#define MAX_HOPS 3
#define MAX_HOPS_FROM_AP 1
#define MAX_APP_PAYLOAD 17
#define DEFAULT_LINK_TOKEN 0x01020304
#define DEFAULT_JOIN_TOKEN 0x05060708
The compiled SimpliciTI.lib hard codes smpl_config.dat (converted for
include file use) parameters to
#define NUM_CONNECTIONS 2
#define SIZE_INFRAME_Q 2
#define SIZE_OUTFRAME_Q 2
#define END_DEVICE

John Heenan, 30 September 2008

[Non-text portions of this message have been removed]
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Discussion Groups | MSP430 | ZGUS radio library for eZ430-RRF3500 with simple radio modem source code app

ZGUS radio library for eZ430-RRF3500 with simple radio modem source code app - John Heenan - Sep 30 13:05:34 2008