Hi, > Am 23.08.2016 um 00:42 schrieb Sebastian Reichel <sre@xxxxxxxxxx>: > >> I am not a specialist for such things, but I think you have three >> options to connect bluetooth: >> >> a) SoC-UART <-> BT-Chip-UART-port >> b) USB-UART (FT232, PL2303 etc.) <-> BT-Chip-UART-port >> c) USB <-> BT-Chip-USB-port (not UART involved at all) >> >> Case c) IMHO means you anyways need a special USB driver for the BT-Chip connected >> through USB and plugging it into a non-embedded USB port does not automatically >> show it as a tty interface. So you can't use it for testing the UART drivers. >> >> BTW: the Wi2Wi W2CBW003 chip comes in two firmware variants: one for UART and >> one for USB. So they are also not exchangeable. > > Yes, let's ignore option c). > I'm talking about UART only. If the > chip has native USB support, then that's a different driver. Exactly. > >> Variant b) is IMHO of no practical relevance (but I may be wrong) >> because it would mean to add some costly FT232 or PL2302 chip >> where a different firmware variant works with direct USB >> connection. > > Well for some chips there is not native USB support. But my scenario > was about development. Let's say I have a serial-chip and I want to > develop a driver for it. It would be nice if I can develop the > driver with a USB-UART Yes it would be nice, but is this a thing with significant practical relevance? Usually you have to write drivers for a complete device where the slave chip is already wired up to a SoC-UART. Sometimes you can get a bare chip where you can connect to an USB-UART. But someone has to design that piece of special hardware for you. If you are really lucky there is an evaluation board. And in that case I would use a RasPi or BeagleBone and tie up directly to some SoC-UART instead of using an intermediate USB-UART adapter. Because it is more close to timing relations to the final SoC based design. > and then use it on my embedded system. > > There are usb-serial devices, which could benefit from support > btw. I would find it really useful, if the Dangerous Prototype's > Bus Pirate would expose native /dev/i2c and /dev/spi and it's > based on FT232. Oh, that is an interesting device I didn't know yet. > >> So to me it looks as if you need to develop different low-level >> drivers anyways. > > No. You say, that option b) is irrelevant and assume, that every > serial chip also has native USB support. I just assume that b) is rarely used because there are alternatives. Although it would be a nice option. Anyways, while following the discussion this is not the most important facet of the overall topic. BR, Nikolaus
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