User's Manual

Bluegiga Technologies Oy
Page 53 of 71
9 Software Stacks
WT32 is supplied with Bluetooth v2.0 + EDR compliant stack firmware, which runs on the internal RISC
microcontroller.
The WT32 software architecture allows Bluetooth processing and the application program to be shared in
different ways between the internal RISC microcontroller and an external host processor (if any). The upper
layers of the Bluetooth stack (above HCI) can be run either on-chip or on the host processor.
9.1 iWRAP Stack
PCM I/O
Host I/O
Radio
48kB RAM Baseband MCU
LC
LM
HCI
L2CAP
RFCOMM SDP
iWRAP
UART
Host
I/O
PCM
Figure 34: iWRAP Stack
In Figure 34 above, the iWRAP software solution is described. In this version of the stack firmware shown, no
host processor is required to run the Bluetooth protocol stack. All software layers, including application
software, run on the internal RISC processor in a protected user software execution environment known as a
Virtual Machine (VM).
The host processor interfaces to iWRAP software through one or more of the physical interfaces, which are
also shown in the figure 35. The most common interfacing is done through the UART interface using the
ASCII commands supported by the iWRAP software. With these ASCII commands, the user can access
Bluetooth functionality without paying any attention to the complexity, which lies in the Bluetooth protocol
stack.
The user may write application code to run on the host processor to control iWRAP software by using ASCII
commands and to develop Bluetooth powered applications.