hoperf.com Q&A

Wolfgang Spraul wolfgang at sharism.cc
Mon Sep 27 00:23:27 EDT 2010

this is a bit old, I visited HopeRF about 2 months ago but never got
around to sending the mail...

I uploaded a few pictures to the wiki
...and here is my Q&A session with them...

Q: Is your RF IP licensed from Silicon Labs (for example RFM12B)?

A: Yes, HopeRF is the biggest Silicon Labs customer in China. All
current RF ICs are licensed from Silicon Labs. The RFM-12B was
originally based on an Integration RF IC, Integration was then
bought by Silicon Labs. The 22B/23B is the first original Silicon
Labs RF IC used by HopeRF. HopeRF is now working on modules
integrating an MCU (RF60, RF70), and on 2.4 GHz modules.

Q: Can 3 or more devices talk to each other?

A: It's better with 22B/23B, more difficult with 12B. The length of
the FIFO in 12B is only 2 bytes, in 22B/23B it is 64 bytes, which makes
package handling much easier. Also, the 868 or 915 bands would be better
suited to implement hopping systems. The 868/915 Mhz bands are about
20-30 Mhz wide, the 433 Mhz only about 3 Mhz. So on 433 maybe you can
only make 5 devices talk to each other, on 868/915 up to 20. 433 will
have longer distance and less noise.

Q: Do you know any other customer using Linux?

A: Some Chinese phones include HopeRF modules, but they don't know the
kernel, maybe WinCE. We explained that we would write a GPL Linux driver,
they got it and like it.

Q: Can you transmit voice over HopeRF modules?

A: Low quality like phone call should work, one customer is offering
voice calls with 12B modules. Music quality cannot be achieved. Only
half-duplex, i.e. all modules can only either transmit or send at any
given time.

Q: When were the modules introduced?

A: RFM12B: 2006, RFM22B/23B: 2010

Q: What is the difference between 22B and 23B?

A: 22B has 20dBm TX max, 23B only 13dBm. They said both support 8
transmit power levels, increasing by 3dBm, which I don't quite
understand but that's what they said.
Some markets such as AMR (automatic meter reader) have high power

Q: Are the 12B and 22B/23B modules the same size?

A: No but almost. Pin positions are different. 22B and 23B are pin
compatible and replaceable.

Q: Can the 12B and 22B/23B talk to each other?

A: 22B and 23B can talk to a 12B module if they use FSK. 12B can do
ASK/OOK but few customers use it, maybe needs some hacking. The chip
supports OOK/ASK but the module is designed for FSK.

Q: Do we have to have an antenna?

A: Yes. The modules do work without antenna, but lab only, very short
distance. PCB antenna is OK and should give performance comparable to
wire antenna, but may need a lot of PCB space. Module needs a 50 Ohm
wire antenna, length 1/4th of the wavelength. Most HopeRF customers
use wire antennas, few use PCB antennas. Wire antenna length for
868/915 is ca. 76mm, for 433 Mhz ca. 156mm.
HopeRF documents about antennas:

Q: What do you think about TI CC11xx chips?

A: They think TI functionality is similar to their modules, with difference
maybe in transmit power. 22B/23B can do narrow-band. For communicating
with TI CC11xx, 22B/23B can do it, with 12B it's harder but also possible.
22B/23B are more flexible on RF operation, synchronize word and header
can be changed. They are probably cheaper than TI.

Some other tidbits:
*) all modules are offered in 3 packages: DIP, SMD1 (large crystal),
   SMD2 (smaller crystal)
*) price is the same for DIP and SMD1, SMD2 is about 30 US cents more
*) nordicsemi.com is an important competitor, a much larger company
   with their own RF ICs. They think nordicsemi modules are more
   expensive, they have a product that is better than the 12B, but not
   as good as the 22B/23B, and they may have less choice in module
*) HopeRF sold about 12kk modules in 2009, from those 1-2kk directly to
   foreign countries, 2-3kk to HK & Taiwan, the rest to mainland China
   (but mainland factories may in turn export the finished products).

Since this Q&A session, work on the HopeRF modules on our side has
more or less stopped (a number of people have the modules and
expressed interest originally, so it may resume).
The stop is partially because of Werner's dire assessment of the 433
Mhz band, and our unwillingness to consider a non-global solution
with 868/915, making two different versions of NanoNotes. Even more
importantly Werner has since started the much more promising ben-wpan
project, more about that in a sec...
As a last note about 433 Mhz for now: Not everybody thinks it's dead.
To see it in a more upbeat way, checkout Dash7 at http://www.dash7.org
Note that Dash7 is using the proprietary and patented ISO 18000-7.

Back to ben-wpan: The ben-wpan project is a home grown RF module in
the 2.4 GHz band using 6LoWPAN.
ben-wpan homepage: http://projects.qi-hardware.com/p/ben-wpan/
6LoWPAN: http://en.wikipedia.org/wiki/6LoWPAN

If we can get this to work, it would fit better into our copyleft
hardware roadmap than HopeRF modules, especially the newer ones
with integrated MCU. A recent ben-wpan picture:
(if you only click on one link in this mail, click on this one!)

I will probably go back to HopeRF in a few months, to tell them that
development using their current modules is stalled on our side right now,
and to introduce ben-wpan. Who knows they may even want to manufacture it.
So much for HopeRF,

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