CC2541 一个包可以发送超过20个字节的数据吗？

如题

不可以。

The GATT spec allows for a maximum attribute length of 512 bytes. That is not related to how much can be sent over the air in one packet.

The maximum amount of application data that can be sent in one BLE Packet is 20 Byte, due to L2CAP limitation. This is the Core spec applying for all BLE implementations, including iOS Core Bluetooth.

你好，

是在不行你就用CC2640吧。

CC2640支持BLE 4.2协议栈，最大的payload从20个字节有很大的提升，最大支持251byte per package.

https://github.com/ti-simplelink/ble_examples/blob/master/docs/throughput_example.md

你可以用CC2640，最新2.2的SDK支持到BLE4.2，支持的包长可以更长。CC254X目前最新的BLE1.4.2 SDK还是支持的BLE4.0协议栈。

The data length extension feature allows the LE controller to send data channel packet data units (PDUs)
with payloads of up to 251 bytes of application data, while in the connected state. Furthermore, a new
PDU size can be negotiated by either side at any time during a connection. Previously, the controller’s
largest data channel payload was 27 bytes. This increases the data rate by around 2.5×, compared to
Bluetooth Core Specification version 4.0 and 4.1 devices (if both devices support extended packet length
and are configured properly).