Bluetooth SDK Forum Discussions

[MaKo_4657646]

In SPP, if the MTU of the connection destination is small, that value will be used.
Therefore, it seems that the length sent by wiced_bt_spp_send_session_data cannot exceed the negotiated MTU value.
If the MTU value is exceeded, no transmission will be performed.

wiced_bt_spp_rfcomm_get_peer_mtu will result in a link error.
How do I get the MTU value used when connecting?

[SheetalJ]

Hi @MaKo_4657646 ,

Ideally this API is the way to get peer MTU when using SPP. Check if you have header file added in your code. Can you share the screenshot of the error you are getting? 

[MaKo_4657646]

The following error is output when linking.

c:/users/i012890/modustoolbox/tools_2.2/gcc/bin/../lib/gcc/arm-none-eabi/9.3.1/../../../../arm-none-eabi/bin/ld.exe: C:/TOOL/ModusToolbox/MTW/spp/build/CYBT-483056-EVAL/Debug/spp.o: in function `spp_connection_up_callback':
C:\TOOL\ModusToolbox\MTW\spp/spp.c:418: undefined reference to `wiced_bt_spp_rfcomm_get_peer_mtu'

Only CYW20819A1 and CYW20820A1 are valid in spp_lib.c. So I don't think wiced_bt_spp_rfcomm_get_peer_mtu can be used with CYW20719B2.

#if defined(CYW20819A1) || defined (CYW20820A1)
/*
* get the rfcomm peer_mtu
*/
uint16_t wiced_bt_spp_rfcomm_get_peer_mtu(uint16_t handle)
{

Is there an API that can be used instead?

[SheetalJ · Accepted solution]

Unfortunately I dont think there is any other API to perform this operation.