Parameters tweaking to maximize throughput on MSP-430.

Hi Stonestreet,

I need to pass to 921600 bps, but I have buffer overrun error detected in UART interrupt handler after few seconds.

I'm working on MSP430F5438A.

Please advise ...

Thanks

Mikael

Hi mikael,

Could you tell us what clock rate you are using?  For running it at 921600 you need to use the maximum supported rate. Also, could you tell us what interrupts are there in your setup? 

Best Regards,

Stonestreet One.

Hi,

I working at 25MHz.

I have two other interrupt in my application : DMA from another UART channel and 1 ms timer for the tick of the stack. both are very short....

Hi mikael,

The issue could be that the the other interrupts are preventing the servicing of the UART interrupt. Could you tell me how much time the other interrupts take?

Best Regards,

Stonestreet One.

Hi Stonestreet support,

I have one timer interrupt each 1 ms, and one DMA interrupt one another UART channel. I optimized them and they are very short.

Did you have tried to redesign your UART/HCI driver to use one DMA channel, to receive bytes at least ? (My application is running on MSP430 ).

I think it is the best solution to improve the reliability of the communication between microcontrolor and HCI chipset ...

The interrupt handler of your UART driver seems to be a little bit heavy.

Thanks

Mikael

Hi Mikael,

We don't use DMA at the UART/HCI driver at the moment. It is handled in the HCITrans code and the source code for that is provided in case a customer wants to change or improve the implementation of this layer.

Best Regards,

StonestreetOne.

Hi stonestreet,

There is not any DMA connected on USCIA3, so we have to use the interrupt style for the driver.

Anyway, I fixed my problem with buffer overrun, but at 921600 we don't work at 203kbps. We are working at less than 192kps.

Please help me to make my stack more faster. 

Another question: What is the difference between Spp profile and rfcomm socket ? How many bytes it will be possible to save in the transmit operation ?

Thanks

Mikael

Hi mikael,

I am working on the msp430f5438a, want to calculate the 1ms tick count for throughput calculation. Can you please suggest me  which type of interrupt you are using and this interrupt sourly not effect the main thread.? My project was struck exactly at this place.

Thanks and Regards,

Ramana.

Hi Ramana, 

I don't understand what you need ?

If you are talking about the transmit throughput so you can using the 1 ms timer, count 1000 ticks, and during these ticks, count how many bytes you sent. The function SPP_DataWrite is a blocking function and return the number of bytes really sent. So don't count the number of bytes you want to send, but only the number of byte really sent.

In SPP example, you will see that the bluetooth stack is synchronized on 1 ms timer interrupt.

thanks,

Mikael

Hi Stonestreet One,

Stonestreet One Support said:

You can set the baud rate the SPP is operating at by using the command SetBaudRate. For example to set a baud rate of 921600, type the following in the command prompt

SPP+LE>SetBaudRate 921600

 

It will return the following.

 

HCI_Reconfigure_Driver(921600): Success.

 

You can also try to tweak the UART buffer sizes in file HCITrans.C.

Change the

#define DEFAULT_INPUT_BUFFER_SIZE to 1042 and

#define DEFAULT_OUTPUT_BUFFER_SIZE to 384.

 

Note: Changing these values may cause the MSP-430 to run out of memory. You can increase the amount of memory allocated by changing the BTPS_MEMORY_BUFFER_SIZE. This option can be found in CCS 5 by going to Project->Properties->Advanced Options->Predefined Symbols. Double click on BTPS_MEMORY_BUFFER_SIZE in the pre-defined names to change it. If you are using IAR, Project->Options->C/C++ Compiler->Preprocessor(Press the arrow button if you can’t see it initially). We set it from 3600 to 9600 and was able to run all of the changes mentioned here. You should be able to set a RFCOMM frame size of 50, Transmit Buffer size of 300 and Receive Buffer  size of 300 and have the DEFAULT_INPUT_BUFFER_SIZE and DEFAULT_OUTPUT_BUFFER_SIZE at default values in HCITRANS.C without increasing the memory.

Below is a table that notes some of the throughput values and parameter combinations.

 

Data Transfer from Sample Application to MSP-430

ConfigParams	BaudRate	UART Buffer Sizes	Throughput
50 100 300	921600	128,64	197Kbps
50 100 300	460800	128,64	186Kbps
50 100 300	921600	1042, 384	203Kbps
50 100 300	460800	1042, 384	190Kbps
50 300 300	921600	128,64	203Kbps
50 300 300	460800	128,64	190Kbps
50 300 300	921600	1042, 384	209Kbps
50 300 300	460800	1042, 384	190Kbps
50 300 500	921600	128,64	252Kbps
50 300 500	921600	1042, 384	254Kbps

 

Data Transfer from MSP-430 to Sample Application

 

ConfigParams	BaudRate	UART Buffer Sizes	Throughput
50 100 300	921600	128,64	158Kbps
50 100 300	460800	128,64	150Kbps
50 100 300	921600	1042, 384	159Kbps
50 100 300	460800	1042, 384	150Kbps
50 300 300	921600	128,64	198Kbps
50 300 300	460800	128,64	192Kbps
50 300 300	921600	1042, 384	203Kbps
50 300 300	460800	1042, 384	193Kbps
50 300 500	921600	1042, 384	203Kbps
50 300 500	460800	1042, 384	193Kbps

SetBaudRate() function sets baud between Host and BT module, but what is the baud between two BT modules ie. speed in Kbps between two BT modules, or is that the same?

How can I calculate the Troughtput for default baud 115200?

Regards,

David.

Hi David,

You can calculate Throughput on your own "TP = (Number of Bits/1000)/Time in Seconds". Make sure to converts the amount of data to bits.

Hi Sundeep,

Sundeep Mandava said:

You can calculate Throughput on your own "TP = (Number of Bits/1000)/Time in Seconds". Make sure to converts the amount of data to bits.

The Time, do I get this from Baud or I have to measure it ?

Regards,

David.

Hi David,

You have to measure it.

Hi Sundeep,

I'm measuring the rf256x evulation board.

Server->SPPLEDemo, advertise on

Client->SPPLEDemo, connectedLE to Server.

Measurement server board.

When connected and advertising:

this happens every 200ms.

When sending 10B:

Only one occurrence.

Period=600us

Bits=8*10=80

TP=(80/1000)/(0.0006s)=133.33kbps ??

Regards,

David.

Hi David,

It will be accurate if you take the time from the sniffer log.

Usually the throughput test is conducted in a shield room, as it will depend on the environment where you are testing it.

Hi Sundeep,

Thank You.

Is there some sniffer software on TIwiki  for rf256x(PAN1323) board to used it like sniffer? I can't find it probably I missed it.

Regards,

David.

Hi David,

No, see http://www.fte.com/products/fts4bt.aspx