Programming the USB1287 or the ATtiny861

Reprogramming of the AT90USB1287 (USB gateway and board controller) and the ATtiny861 that controls the Charger is possible, and may be required to use the latest version of the firmware. It is recommended to always upgrade to the latest version of the firmware, found on, to ensure that the firmware match this documentation and operates accordingly. The firmware source code running in these devices are available, but only as an extra service: These devices are part of the development platform, not part of a reference design. Therefore the source code for these devices are provided as is, and with limited support. The product supported fully is the source code for the reference designs such as the SB201.

One case where update of the USB1287 firmware can be relevant is if a different communication protocol is desired to be used between the smart battery and the host. During the development it can be desired to use the USB1287 as a gateway to communicate with the smart battery via this interface/protocol. Changes and extensions to the communication interface/protocol are left to the users to implement. To program the ATtiny861, the USB cable must be disconnected, and the USB1287 will release the SPI-lines which are used for inter-communication.

Figure 1. Programming Interfaces for USB1287 and ATtiny861