Initial F310 CPU design



Here is the first proto design of a repackaged component.


It is a SiLabs F310 CPU. This little device is a 25MIPS CPU, with all the bells and whistles you would expect

from a 8051 device and so much more.

We have taken this device and added to it:

(1) A crystal oscillator section,

(2) programming port,

(3) diagnostic LED,

(4) quick access to 4x test points to add power and RS232 and lastly

(5) 2x 16 pin 100mil/2.54mm spaced connector.


Looking simplistically at the board you only have to apply power and program it... and be up and running.


The little board measures +- 42mm by 25.4mm

Can we go smaller?

Yes, but for now that is not the real aim of the product.

We can use a QFN package (5x5 mm), smaller crystal, 0603 resistors and capacitors.

But for the meanwhile the specification was the following: We designed the board (and other to follow) to fit on prototyping breadboard.

This means that there is a maximum of 22.8mm between the 2 connectors (constraint number 1).

Furthermore, the connectors have a 2.54mm spacing creating a 42mm length for 16 pin

(will be more for larger modules like GSM) ...thus constraint number 2.

Lastly the connectors must be single in line (SIL) as DIL (dual in line) connectors

will cause shorts on both breadboard and Veroboard. (constraint number 3).

If there is a requirement for 1.27mm or 2mm spaced connectors then you must order that as a custom design.


As said above the module will fit standard breadboard. The picture shows a 1:1 printout where the

connectors will be.

The design leaves you a row of pins at the top and bottom. Each pin, of the CPU,

has been brought out on the J1 and J2 connectors. The programming port is a standard

10 pin IDC mail connector, so you can use the EC2 or EC3 programmer without any modifications.


Connector options

The boards/modules will shipped with 2 connector options:

(1) Less expensive IDC connectors suitable for Veroboard or custom PCB mount.

(2) More expensive turned pin connectors suitable for breadboard as well as Veroboard and custom PCB.


What else will you need?

You will need to buy a Silabs EC3 (USB) programmer (this should be around R440 ex VAT depending on the wonderful exchange rate).

The EC2 (RS232) and EC3 (USB) can both program and debug and also do JTAG (for the larger devices)

These guys sell a 4 port programmer ( which is ludicrously expensive.

If you know your stuff you can build your own programmer. We are planning to design one ourselves, but you cannot debug.

(we already have a dirt cheap Altera ByteblasterMV cable and some associates are designing us a cheap ARM7/9 programmer with

a GNU toolchain).

The 4kbyte C compiler and IDE is freely downloadable from Silabs's website.

If 4kbyte is too small for you then you will either have to fork out lots of money for the full Keil C compiler version  or

download a perfectly free GNU compiler from


You will also receive a link where you can download the test/demo software.

With the module you will receive a printed schematic and layout, but you will be able to download

everything in software format as well.



What other module sizes will be produced?

The horizontal length of the modules will be pin number dependent.  These will range from 8,16, 24, 32 to 48 pin.

This will result in lengths from +-18mm to 63mm

The vertical width is breadboard dependent. This will range from +-13mm and 22.8mm (for single breadboard) to 52mm and 74mm (for double breadboards).


So what is next?


We need to prototype the first units. Normally we can only get 5 to 6 prototype boards in less than a week, so we

won't be able to take larger orders. After that we will order large volumes. From the PCB and assembly costs we

will determine the selling price for both single unit and larger volumes.


The proto units will also be for sale. For now I will just accept orders from South Africa, especially the Pretoria/Johannesburg area,

in case there are major problems.


Which modules are next?

Currently we are producing the modules for our own use, so we are designing (for the next 2 weeks) to cover

the following requirements:

(1) RS232 converter: 3.3V/5V to/from +-12V PC levels.

(2) USB RS232 converter:  3.3V/5V to/from +-12V PC levels.

(3) Silabs F120 main board.

(4) LCD interface: 128 x 64 mono, with 3.3V serial interface.

(5) Cinterion MC55i GSM modem.

(6) Wavecom Q26 GSM modem.

(7) ezRide GPS receiver.

(8) Jupiter 32 (low power) GPS receiver.

(9) Silabs F305 CPU including Cap Sense circuit.

(10) USB to RF (Nordic nRF9E5 8051 CPU) with built-in 80 meter patch antenna.

(11) Power supply: 12V/24V to 3.3V, 3.6V and 5V (GSM modems)

(12) Power supply:12V/24V to 3.3V only (for Silabs CPUs)


All of the modules above, except (3),(4) and (8), are already in schematic and PCB format and just need to be

converted to module format.


During last week a client made the suggestion to make a generic motherboard where one can just plug in modules

without great effort and reduce time to market. By doing this you can test different CPUs, GSM modems and GPS receivers

 on the same platform.  Will keep you updated.



Payment options.

For now we will accept cash (who wouldn't?), EFT bank transfers and credit cards (via

For cash and EFT we will discount you the 4.9% transaction fee charged on credit cards (but this apply only to South African

clients for now).

We are VAT registered and will be able to provide you with an official VAT invoice.