Centurion MicroElectronics is an importer and distributor of industrial PC products sourced from all over the world. From time to time the company gets a client with a unique requirement not covered by standard products from its suppliers. This, and the fact that the Internet is shrinking the world such that distributors who do not offer added value are always at risk of being bypassed by the clients, led the company to consider manufacturing its own embedded PC CPU card. In this article CME tells the story.
Taiwan makes millions of motherboards at a fraction of the cost that South Africa could - but this is not true for the industrial/embedded PC field. Here, volumes are a lot lower and in SA we can match their prices. When competing against Europe and the US we can also easily better their prices.
Embedded PCs are used in all sorts of industrial applications. The embedded PC is treated like a building block to do a specific function and quite often no screen or keyboard is used. In many cases a 386SX is quite fast enough to do the job and various chip manufacturers are even designing new 386/486 chips for this market.
At first we believed that designing one's own PC would require a huge financial outlay in hardware and software (BIOS), design engineers, and development tools, and would take years to complete. Since most low-end boards we import did not seem too complex we decided to look for an easy way to acquire the design capability.
Hardware
Our design is based on the M6117C component from ALi - not referred to as a 'CPU' but as a 'MCM' (multi chip module) because of the high level of integration. The M6117C contains a 386SX40 CPU, keyboard controller, DRAM controller, interrupt controller, RTC (realtime clock) and a timer/counter module all integrated into one 208-pin QFP IC. To this is added a BIOS chip, minimum one DRAM chip and frequency generation hardware and some simple discretes. This comprises the PC hardware.
ALi e-mailed the M6117C datasheet and the schematic design was purchased in the US from a BIOS supplier. Since such suppliers are keen to sell their BIOSes they charge virtually nothing for their designs. We copied the design from Orcad into our Edwin CAD package (originally purchased for under R2000) and made some simple modifications to support our selected connector types, battery and other component packages. The six-layer PCB was made by TRAX and the components were sourced from the US and Taiwan (Taiwan being nearly four times cheaper than the US on the M6117C). A local soldering service soldered the components to the PCB - and we had our hardware.
BIOS
A couple of years ago companies had to buy a BIOS development kit costing in the region of $80 000 and then spend many man-months to create and debug the BIOS. These days one supplies the BIOS company with a card's details and the company makes a BIOS to match the card - at a fraction of the cost.
A problem that we experienced was that most of the bigger BIOS companies showed no interest in helping us. Possibly one needs to fly to the US, see them directly and also requires hundreds of thousands of BIOS licences before they become interested. After much e-mailing, AMI in Taiwan was prepared to help us. After paying a set-up fee one has to purchase at least 200 BIOS licences at a time. Another BIOS option was our schematic supplier in the US. Its BIOS - called T-Bios - offers some special capabilities and simplifications. Basically it has no set-up screen, only supports 1,44 Mb stiffy drives and the hard drive is auto-detect by default. Date and time is set from DOS. After booting one gets the board information on the screen with a C:\ prompt. An additional feature is the fact that a flash disk (emulating A:\) is also included in the BIOS 's flash chip. Instead of a 29F010 (128 Mb) BIOS chip one uses a 28F040 (512 Mb) chip. Of this 128 Mb is used by the BIOS and the remaining 384 Mb is available to the user as a flash disk. For small DOS applications this provides more than enough storage space at a very low price and no extra board real estate is needed.
Debugging
For debugging the prototype we used an AMI BIOS. It is important here to have the correct DRAM type. The M6117C is specified to work with either FP or EDO DRAM but FP is the only type that we found to work with our imported boards. On the frequency side one needs to supply 32 kHz, 14,31MHz and 80 MHz. An eight-pin IC (ICS503) can be used to generate 80 MHz from 14,31 MHz. The prototype card was fitted to a backplane and a VGA and multi I/O cards were added.
We powered up.and nothing happened. There was at least activity on most of the pins, and after some measurements it became apparent that one of the DRAM address lines was floating. This turned out to be a CAD mistake on the schematic. After one modification it booted fine. A 386SX is no 'Pentium III' but it worked well and passed all the 'Checkit' tests - save for the RTC time test. The RTC design requires a 20 MOhm resistor and a 10 pF capacitor, of which we had neither at the time so it was left unpopulated. After adding these, the problem disappeared. (The board is also Y2K compatible)
The next phase
So far our board has an ISA bus interface and a keyboard/PS2 mouse interface and a working speaker. We also needed serial ports, parallel port, stiffy interface, an IDE hard disk interface and some sort of flash support. To provide this we selected the FDX37C669QFP chip from SMsC and added circuitry to interface to a M-Systems disk-on-chip. We have already designed a separate PC104 card with these features. Once fully debugged we plan to combine this with our CPU card to create a marketable product. We are also currently working on an Ethernet card based on the RTL8019 chip from Realtek, and a further goal is to add VGA capability. The idea is to get CPU cards with/without ethernet, with/without VGA in various form factors such as PC104, ISA bus size and wafer size. We have teamed up with a PC104 I/O card designer and hope to get a range of PC104 I/O cards as well. The first card is a 48 way DIO card.
Obviously a 386SX40 has speed limitations, and after investigating various 486 CPU options we decided to design around the Mach-Z 486DX component. This is another highly integrated IC that even includes on-chip BIOS. A problem is that the pins on this module are BGA which has its own challenges.
Marketing
The intention is not to only design the cards but to also sell them and CME plans to market both locally and internationally. The first CPU product will be a low-cost PC104 CPU card with disk-on-chip (DOC) and standard I/O suitable for access-control type applications. Internationally CME plans to try the US market first, with the assistance of some ex-South African contacts who can assist with marketing support. We also plan market over the Internet and perhaps in certain US magazines.
CME may also enter the customisation area where a product is tailored to certain requirements. An example is to add A/D functionality to the CPU and repackage it in a custom form factor. Here the client would be charged for customisation process but will get exactly what he needs at a reduced cost per unit.
The part number of this CME prototype card is the PW104CPU (P and W are the initials of the two individuals involved in its development up to now). The design price of the first module will be in the region of US$90 (around R700) in 100+ quantities.
For further information about this product contact either Peet or Werner at Centurion MicroElectronics, (012) 661 4576, [email protected]
| Tel: | +27 12 666 9066/8 |
| Fax: | 086 402 8978 |
| Email: | [email protected] |
| www: | www.cme.co.za |
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