How much of the STM32 is available for running the customer's application?
Can I push content to a phone if the Bluetooth is switched on? I'd like to send electronic coupons.
What are standard Bluetooth ranges and RF power based on industry trends today?
Q: What is the maximum data rate for a Bluetooth spec v2.1 module with EDR?
A: The maximum Bluetooth +EDR symbol rate is 3M bps, but it's based on the protocol's 2-way (full duplex) data rate with the EDR modulation. This is a common quote seen in many Bluetooth specs.Q: How much of the STM32 is available for running the customer's application?
The 2M bps is a more accurate "real world" usage of this. It's basically a maximum 1-way data transfer, with some over-head bytes.
Modules will have a bottleneck at the UART (max 921k bps) for pumping this data so quickly. However, data could be internally expanded or generated, and then sent at this rate. Or, a faster SPI interface may be used as well.
A: Our stack uses a max of 12 MIPS at very high data rates, typical is about 3 MIPS. This leaves 60+ MIPS on the STM32. Basically, the stack doesn't push it too hard.Q: Available Flash?
A: We use 140K for full implementation, and 80K for limited/minimal versions. The STM32 has 256K Flash, and 384K/512K are options. There is plenty of Flash for most applications.Q: Available SRAM?
A: We use about 40K for full implementation, and 12K for limited/minimal versions. This STM32 has 48K RAM, and the D & E versions have 64K RAM. They are all the same package, and can be used interchangeably. Lower data rates and limited service/device discovery saves RAM if needed.Q: How many I/O lines are available?
For the BT-11 modules:Q: Can I push content to a phone if the Bluetooth is switched on? I'd like to send electronic coupons.
A: I/Os: 16 general I/O's, 4 A/D, 1 DAC, many of the STM32 I/Os are available. Other pins can be used for I/O if not needed.
Serial I/O: 3 x UART, I2S, SPI, I2C, USB
A: YES, we can help you with this application. We have implemented the following BT profiles that allow us to push content to a cell phone. We can use the OBEX OPP (object push profile), GOEP (generic object exchange), or BIP (basic image push) profiles.Q: Can you connect a digital camera to a Bluetooth module using OPP or BIP profiles to send images from the camera? What is the SPI specifications and maximum speed using SPI?
A: Our BT-11 Cortex based modules, with our initial OBEX profiles, will support this application. The SPI can support up to 12M bps on our BT-11 but has a maximum speed of ~2M bps over the BT link, using a SPI.Q: What are standard Bluetooth ranges and RF power based on industry trends today?
A: Currently, a class 1.5 device is becoming more popular. Class 1.5 is more powerful than a class 2 device, but less than a true class 1 unit. However, the cost is the same as a class 2, because the basic RF chip can supply more power in the first place.Q: Is there any possibility of letting us as customer develop a higher level function (with own code) by ourselves in the ARM controller? For example, leave "open" above SPP, or perhaps already at HCI.
These newer Bluetooth chips, class 1.5, are closing the gap to traditional class 1 configurations. In our case, ST Micro is now offering a v2.1 chip, with improved performance from our previous 2.0 chip. Both have better range than older v1.2 chips. So, a module with the v2.1 chip reaches around 60m indoor (about 3x outdoor). Our v2.0 modules reaches 30-35m.
A BT-11, with full class 1 range, would reach 100-120m. However, a BT-11M with just an optimized class 1.5, at 60m+, may be a better choice. With continuous chip improvements, an 80m+ class 1.5 device is not very far away.
A: The Software Development Kit (SDK) for the Cortex based platforms have features that are quite advanced:
Stack layers are provided as libraries Customers may develop applications into the ST Microelectronics' ARM processors Support the IAR “C” compiler We can supply modules pre-loaded with your application images