Atmel AVR390
3
8463A-AVR-11/11
3 Interfaces
3.1 USB interface
The USB interface on the Atmel ATAVRBM300 module is USB Type B. The
ATAVRBM300 connects to a host computer via this interface. The ATAVRBM300 is
also powered by the USB port from the PC. The PC must deliver minimum 50mA to
power the ATAVRBM300. USB (USB 1.1, HID communication class) is used to
communicate between the PC and the ATAVRBM300. A PC USB driver is included in
Atmel AVR Battery Studio 2. This PC software must be installed before connecting
the ATAVRBM300 the first time.
3.2 Interfaces to device
The ATAVRBM300 supports four communication interfaces: SMBus/TWI, SPI, UART,
and single-wire UART. A 10-pin flat parallel cable includes all the signals from the
ATAVRBM300.
Table 3-1.
Pins definition.
Pin number
Pin name
Description
1
SDA
SMBus data pin
2
SCL
SMBus clock pin
3
TXD
UART transmit pin
4
RWD
UART receive pin
5
SCLK
SPI serial clock
6
MISO
SPI Bus Master input/Slave output
7
MOSI
SPI Bus Master output/Slave input
8
/SS
SPI Slave select input
9
R/T
Single-wire UART transmit/receive pin
10 GND Ground
Figure 3-1.
10-pin header definition.
3.2.1 SMBus
To use the SMBus interface, three pins are required: SCL, SDA, and GND. SMBus
specification v1.1 is supported.
