just asking for some reassurance really, probably a novice question. Thank you in advance for any advice.
I am building this project:
to control a SID audio chip from a Commodore 64 via a Teensy microcontroller. I have the project working and can control the chip via usb midi. Next I would like to add some flashing lights in the form of some LEDS to visually demonstrate it functioning.
I have the data sheet for the IC: http://archive.6502.org/datasheets/mos_6582_sid.pdf
I intend to add power LEDs for the two power supplies (5v and 9v)
my thinking is that I can also add eight LEDs (and resistors) for pins d0-7 on the chip which will light as data is being sent to these pinsr. In theory I would connect the anodes to the pins, and cathodes via a resistor to ground.
My concern is that the LEDs may themselves interfere with the data being transferred. Some my questions are really; Is there any way to be sure of this other than experimenting with resistor values? Am I missing something and am actually likely to destroy the IC? Would pins A0-A4 be any different?
the doc has this to say about pins D0-D7.
"D0-D7 (Pins 15-22) — These bidirectional lines are used to transfer data between SID and the microprocessor. They are TTL compatible in the output mode and capable of driving 2 TTL loads in the output mode. The data buffers are usually in the high-impedance off state. During a Write operation, the data buffers remain in the off (input) state and the microprocessor supplies data to SID over these lines. During a Read operation, the data buffers turn on and SID supplies data to the microprocessor over these lines. The pins are normally connected to the corresponding data lines of the microprocessor."