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adrian
Joined: 08 Sep 2003
Posts: 92
Location: Glasgow, UK
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| 802.11g cardbus interface |
 Posted: Mon Mar 01, 2004 7:20 am |
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Has anyone tried to do this yet?
I need to hang a CardBus interface onto my product, and was thinking about using the TI PCI1510, as it will handle both the old ISA based PC Card and the newer PCI CardBus version. Unfortunately, the PCI1510 has a PCI interface (and the standard is not free domain) and has a 32 bit address/data interface. I was wondering if anyone had already tried this or had some ideas? |
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SteveS
Joined: 27 Oct 2003
Posts: 126
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| Posted: Mon Mar 01, 2004 8:08 am |
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Do you mean to interface a PIC to PCI?
If so, the answer is no way. PCI is quite involved not just from hardware, but also software.
I could see, maybe, one could make an 8-bit ISA interface with a PIC, and that I think that would be some work; and that is way way way way way way easier than PCI.
If you want to talk to a PC Card - you should be able to do that directly. I think the interface is well documented. Check the archives.
- SteveS |
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adrian
Joined: 08 Sep 2003
Posts: 92
Location: Glasgow, UK
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| Posted: Tue Mar 02, 2004 7:02 am |
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| SteveS wrote: | Do you mean to interface a PIC to PCI?
If so, the answer is no way. PCI is quite involved not just from hardware, but also software.
- SteveS |
I thought that would be the case - but I thought I'd ask anyway.
The PCI interface is complicated, but I was hoping to try and use a cut down version of it. I don't need my PCI chip to be the master, and I don't need the burst-transfer. If I reduced the PCI clock then, possibly something may be achievable. I was hoping to generate some discussion to get me thinking further.
| SteveS wrote: | I could see, maybe, one could make an 8-bit ISA interface with a PIC, and that I think that would be some work; and that is way way way way way way easier than PCI.
If you want to talk to a PC Card - you should be able to do that directly. I think the interface is well documented. Check the archives.
- SteveS |
The PC Card ISA interface can be done with a hand full of logic chips, thats relavively easy - been there done that. |
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SteveS
Joined: 27 Oct 2003
Posts: 126
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| Posted: Tue Mar 02, 2004 7:30 am |
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Yeah, PCI is a strange beast - when you get into it you'll be amazed it works at all. It actually depends on reflected signals to get the timing right - that's why it doesn't use terminators. I spent a lot of time just designing a simple PCI backplane. I don't think you could drive it with standard logic. The bus transactions can get involved too. The driver stuff just got too deep for me (on a PC).
There are some good books on it if you just want to learn more. It's pretty interesting until it puts you to sleep.....
Good luck,
- SteveS |
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regan
Joined: 10 Sep 2003
Posts: 5
Location: Wellington, New Zealand
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| Have you thought of a PCMCIA interface instead? |
| Posted: Wed Mar 03, 2004 1:57 am |
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adrian,
Check out the 802.11 ChipWeb product that iosoft (www.iosoft.co.uk) offer. Their solution utilises 802.11b but could probably be shifted to the g version.
I haven't checked it out thoroughly but I guess they access the card in an 8 bit mode. You might be able to go for a 16 bit mode by adding an 8 bit latch to the design.
regan. |
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adrian
Joined: 08 Sep 2003
Posts: 92
Location: Glasgow, UK
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| Re: Have you thought of a PCMCIA interface instead? |
| Posted: Wed Mar 03, 2004 6:57 am |
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| regan wrote: | adrian,
Check out the 802.11 ChipWeb product that iosoft (www.iosoft.co.uk) offer. Their solution utilises 802.11b but could probably be shifted to the g version.
regan. |
Oh if only it were that simple!
The IOsoft ER21/22 is based on the PC Card or PCMCIA utalising 802.11b.
The CardBus version is in a different league. For one thing, the pinout of the connector is different between the PC Card and the CardBus - but share the same 68 pins. Therefore you have to have a dual interface, one for PC Card and one for CardBus - and then you have to be able to sense which card you have got plugged in and switch the correct supply voltage to the card. That's why I was looking at using the PCI1510 from Texas Instruments, because it does all this for you. Unfortunately, the PCI1510 utalises a PCI interface - because they expect you to put it into a PC environment, rather than trying to embed it into a microcontroller circuit.
Once you start looking into PCI it starts getting scary! Here's a quote I picked up along the way....
802.11g uses CardBus, and operates at a maximum throughput of 54Mbps at 2.4Ghz. CardBus provides a 32-bit multiplexed address/data path, which operates as a PCI local-bus with speeds of up to 33 MHz, yielding a peak bandwidth of 132MB/sec. CardBus accomplishes this by adopting the synchronous burst-transfer orientation of PCI, as well as a bus protocol, which is essentially identical to that of a PCI slot in a PC. CardBus devices are capable of acting as system-bus masters; that is, they can assume control of the system bus (or busses) to effect data transfers.
Now I don't need all of this, my microcontroller will always be the master and the CardBus will be the slave - like they used to do in the good old PC Card days! I was hoping to loop back some of the PCI handshake signals and reduce the clock speed to simplify the interface.
I was hoping somebody out there had done work on PCI stuff who could prod me in the right direction. At the moment I'm pretty close to a sheer cliff top. |
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Ttelmah
Guest
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| Re: Have you thought of a PCMCIA interface instead? |
| Posted: Wed Mar 03, 2004 8:29 am |
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| adrian wrote: | | regan wrote: | adrian,
Check out the 802.11 ChipWeb product that iosoft (www.iosoft.co.uk) offer. Their solution utilises 802.11b but could probably be shifted to the g version.
regan. |
Oh if only it were that simple!
The IOsoft ER21/22 is based on the PC Card or PCMCIA utalising 802.11b.
The CardBus version is in a different league. For one thing, the pinout of the connector is different between the PC Card and the CardBus - but share the same 68 pins. Therefore you have to have a dual interface, one for PC Card and one for CardBus - and then you have to be able to sense which card you have got plugged in and switch the correct supply voltage to the card. That's why I was looking at using the PCI1510 from Texas Instruments, because it does all this for you. Unfortunately, the PCI1510 utalises a PCI interface - because they expect you to put it into a PC environment, rather than trying to embed it into a microcontroller circuit.
Once you start looking into PCI it starts getting scary! Here's a quote I picked up along the way....
802.11g uses CardBus, and operates at a maximum throughput of 54Mbps at 2.4Ghz. CardBus provides a 32-bit multiplexed address/data path, which operates as a PCI local-bus with speeds of up to 33 MHz, yielding a peak bandwidth of 132MB/sec. CardBus accomplishes this by adopting the synchronous burst-transfer orientation of PCI, as well as a bus protocol, which is essentially identical to that of a PCI slot in a PC. CardBus devices are capable of acting as system-bus masters; that is, they can assume control of the system bus (or busses) to effect data transfers.
Now I don't need all of this, my microcontroller will always be the master and the CardBus will be the slave - like they used to do in the good old PC Card days! I was hoping to loop back some of the PCI handshake signals and reduce the clock speed to simplify the interface.
I was hoping somebody out there had done work on PCI stuff who could prod me in the right direction. At the moment I'm pretty close to a sheer cliff top. |
What you haven't said, is what sort of actual data rate you need, and the likely 'range' of devices you need to attach to.
I have done a PCI interface in the past, but at the time it involved using an ASIC, and a _lot_ of development time/money. I cannot think of any PIC based device that would get close to needing the sort of data rates really involved. Unfortunately, there is a move 'away' from simple to interface busses. However one of the easiest (for which quite a few posts have been made in the past), is to consider connecting to a compact flash interface connector, or to USB using one of the bridge interface chips on offer. Both allow relatively 'easy' connections to most/all current generation devices (you can buy a PCMCIA CF card adapter), and represent possibly about 1/100th the work of trying to get a PCI/Cardbus solution built. Data rates can be quite high enough for most applications.
Best Wishes |
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