LAUNCHXL-CC2650: "simpleProfileChar5 array" values are overwritten when more than 20 bytes are received from BLE scanner

Gajendra Singh Sisodia

Prodigy 80 points

Part Number: LAUNCHXL-CC2650
Other Parts Discussed in Thread: CC2650

Hello,

I am using

CCS7.4

Compiler TI V5.2.4

BLE SDK Version ble_sdk_2_02_07_06

Example "Simple BLE Peripheral"

BLE SCANNER app is used to transmit data from android to CC2650

I have modified code as per said by "YK" from this website "sunmaysky.blogspot.com/.../add-write-capability-to-characteristics.html

Then I done following changes

#define SIMPLEPROFILE_CHAR5_LEN 50

I can write 20 Byte from BLE scanner to CC2650 successfully.

BUT when I transmit more than 20 byte the array

simpleProfileChar5[SIMPLEPROFILE_CHAR5_LEN] is overwritten.

NOW THE PROBLEM IS:

When I send alphabets for example data, abcdefghijklmnopqrst, which is stored as 0 to 19 array index that is 20 byte and I get this response where 20 byte are received properly.

as shown in image

But, when I send abcdefghijklmnopqrstuvwxyz which is 26 bytes, array locations from 0 to 5 that is 6 bytes are overwritten and nothing is written at array location after 19. that is array location from 20 onward are blank

and Yes I know that I will have to increase MAX_PDU_SIZE in ble_user_config.h file.

and I have set #define MAX_PDU_SIZE 50

BUT,

why data is being overwritten

Please give me the solution

over 4 years ago

0 YiKai Chen over 4 years ago

Guru 735695 points

I set MAX_PDU_SIZE as 69 and SIMPLEPROFILE_CHAR5_LEN as 30 to test this with LightBlue app and everything works fine.

0 Gajendra Singh Sisodia over 4 years ago in reply to YiKai Chen

Prodigy 80 points

thanks Yikai Chen, I will try the same and revert you back

0 Gajendra Singh Sisodia over 4 years ago in reply to YiKai Chen

Prodigy 80 points

Thank you Yikai Chen,

I tested with as mentioned above.

I am using "LightBlue app" now

Can you please tell me the what can be the upper limit for "MAX_PDU_SIZE" and upper limit for "SIMPLEPROFILE_CHAR5_LEN" ?

0 YiKai Chen over 4 years ago in reply to Gajendra Singh Sisodia

Guru 735695 points

I think max MAX_PDU_SIZE should be 255 and SIMPLEPROFILE_CHAR5_LEN could be 251.

0 Gajendra Singh Sisodia over 4 years ago in reply to YiKai Chen

Prodigy 80 points

Hello Yikai chen Thank you for your valuable response,

I tested with

#define SIMPLEPROFILE_CHAR5_LEN 100

and

#define MAX_PDU_SIZE 200

which results in proper write till 90 bytes.

In my Project cc2650 is expected to receive images over BLE connection. So I need fastest data write to CC2650.

as per the "CC26x0 SimpleLink Bluetooth® low energy Software Stack Developer's Guide"

it says, MAX_PDU_SIZE range is 27 to 255. and The maximum ATT_MTU = MAX_PDU_SIZE -4.

Can you please guide me to get max range

(MAX_PDU_SIZE range is 27 to 255. and The maximum ATT_MTU = MAX_PDU_SIZE -4)

as mentioned in Software developer Guide?

+1 Gajendra Singh Sisodia over 4 years ago in reply to YiKai Chen

Prodigy 80 points

#define MAX_PDU_SIZE 255

#define SIMPLEPROFILE_CHAR5_LEN 220

then used Windows "BLE LE APP" to transmit data instead of android app.

I can now successfully write 220 byte data to CC2650.

Yikai chen Thank you for your Support

0 YiKai Chen over 4 years ago in reply to Gajendra Singh Sisodia

Guru 735695 points

It’s good to know it works now.

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LAUNCHXL-CC2650: "simpleProfileChar5 array" values are overwritten when more than 20 bytes are received from BLE scanner