关于CC2540的问题

TI的工程师，

您好，我有两个关于BLE CC2540的问题，希望能得到您的解答。 

1.我用simpleBLECentral和simpleBLEPeripheral建立连接，发送数据，然后用sniffer去抓包。因为write的流程是master先发一个req过去，然后slave再回一个rsp。但是我抓包发现，这两个步骤是在两个分开的 connection interval中进行的（就是master在第一个connection interval 里面发送req，但是在接下来的的connection interval里面才会收到对应的rsp），为什么不会在一个connection interval里面同时存在一个req和一个rsp呢？这个是BLE协议就这样规定的吗？

2. 我用master 发送数据给slave，发现最多只能发20bytes的数据，用GATT_writeLongCharValue发送，可以超过20bytes，但是抓包发现，实际也是每次发20bytes，只是把大包拆开了而已。我想问下，在BLE协议里面每次最多能发送多少bytes呢？如果换个方向，让slave给master发送notification的话，最多能发送多少bytes呢？

非常感谢！

Best Regards

Logical Link Control and Adaptation Protocol (L2CAP)
Permits upper level protocols and applications to transmit and receive upper layer data packets up to 23 bytes in length

What is connection interval in your current project? And what is slave latency in your current project? 

Thank you for your answering. In my current project, the connection interval is 10ms and the slave latency is 0. So I want to know why write request and write response are in different connection interval. Can you help me? Thank you! 

Can you try to extend connection interval to more longer, like 500ms?

OK, thank you, I will try to do it. I thought this connection rule might be defined in the BLE protocol. So I want to find the reason. Thank you for your instruction.