Friend wanted to give me programmer board for me to try to learn but it use serial RS282 connector, but i don't have it on my labtop. I was told centain USB to serial converter don't work. The best is to build your own using FTDI chip. I wish i knew how to do it. But is there on the market that i can buy that is ready made USB to RS232 (Real or future UART) or even PCMCIA to RS232 (Real or latest UART), eeerrr....cheap? That way, i can get started learning the coder immediately.
Any help would be appreciated.
PS : I seened eBay sell a lot of those USB/PCMCIA to serial RS232 adapter really cheap. Which one will work best?
A PCI-connected RS232 port is identical to the ports built into the motherboard. The built-in ports are logically connected after a PCI bridge, even if they are available directly on the motherboard.
As serial ports, they should be just about 100% reliable. BUT our operating systems are not. Neither Windows nor Linux are designed for abusing an RS232 port with an external adapter for multi-drop use, where the transceiver may need to be switched from transmit mode into receive mode within a fraction of the transmit time of a single byte, to avoid data collisions on the single transmit/receive line.
This is the reason why some MS-DOS applications could do wonders with an RS232 port, while todays Windows machines can't match even with a 10 or 100 times faster hardware. In MS-DOS, the application where in 100% control, with the exception of the interrupts for time, mouse and keyboard. It was the application that decided if and when to perform any disk operations.
A PC-Card adapter may either use the old 16-bit PCMCIA interface, or the newer 32-bit CardBus interface. The 16-bit interface is basically the 16-bit AT-Bus introduced in 286-class PCs. The 32-bit interface is basically a PCI interface. Both solutions should work well, but to the largest part limited by the capabilities of the used OS.
Anyway, because of the limitations of - to a large part - our OS, I do recommend critical timing to be handled by external hardware. With the low price of microprocessors, all programming adapters should contain their own intelligence.
How many laptops have got PCI slots?
Not many laptops have PCI slots, but a number of laptops have PC-Card support. Same thing, but in a different form factor.