#SINCLAIR ZX SPECTRUM KEYBOARD SERIAL#
#SINCLAIR ZX SPECTRUM KEYBOARD CODE#
#SINCLAIR ZX SPECTRUM KEYBOARD PC#

#SINCLAIR ZX SPECTRUM KEYBOARD CODE#

The code and schematics are all free and open to modification, hacking,Р В РІР‚СњР В РІР‚РЋull schematics plus the prototype PCB designed in Cadsoft's Eagle Quick-n-dirty, some better error handling could be added there. There's room for enhancement, the keyboard initialization code is a bit So that pretty much met the design goals. The pinning of the CPLD was made with reference to make the board layoutР В РІР‚СњР В РІР‚С›s easy as possible and ideally fit on a single sided PCB. Also the arrow keysР В РІР‚СњР В РІР‚С›re decoded to the spectrum 'shift' + direction keys. Translated to the spectrum codes for 'shift' and '0'. This is really useful for the AT key 'delete', which is It can also set all the keys in one row as 'pressed' at Spectrum keys in two different rows to be marked as 'pressed' The micro-controller AT keyboard conversion table allows for multiple Reset' high causing the CPLD's internal memory address counter to be reset

After all bits have been written out the MCU pulls 'mem The MCU pulls the clock low and gets the next bit ready to send.Р В РІР‚СњР В РІР‚С›t this falling edge of the clock signal, the CPLD updates its internalР В РІР‚СњР В РІР‚С›ddress counter to point to the next bit location in the 40 bit 'key bits' Onto the CPLD's 'mem-data' line and pulls the 'mem clk' clock input high,Р В РІР‚СњР В РІР‚С›t which point the CPLD stores that key state in it's internal 40 bit Next it puts each bit representing the key state The 'mem reset' line high, then low to set the CPLD's internal addressР В РІР‚СњР вЂ™Р’В¬ounter to zero.

#SINCLAIR ZX SPECTRUM KEYBOARD SERIAL#

The serial shifter for the MCU to the CPLD is very simple, the MCU pulls Status of BOTH those rows onto the databus, just like you'd see happening So if bothР В РІР‚СњР В РІР‚С›ddress line A8 and A10 are low, the CPLD will output the up/down key The bigР В РІР‚СњР В РІР‚С›dvantage of this CPLD approach is that it can simulate this behavior. Time by having more than one address line being low during a keyboard read. on the original Spectrum you could read more than one row of keys at a Why's this design different from others ? Well. The CPLD has effective priority, so it's data is read by the spectrum and

As the ULA is effectively 'isolated' from the specturm databus, Keyboard row and each of the D4 to D0 bits corresponds to a keyboardР В РІР‚СњР вЂ™Р’В¬olumn. The bits areР В РІР‚СњР вЂ™Р’В¬ontrolled by the A8 to A15 address lines. Places onto D4 to D0 the state of the 'key bits' array. Z80 /RD line going low, which is the signal for a keyboard read, and The keyboard using a z80 'IN' opcode the CPLD detects the IORGE with the Information, is handling I/O reads from spectrum ! When the spectrum reads The most important thing the CPLD does, apart from storing the key States of up or down and passing these to the spectrum when requested. See the AVR sourceР В РІР‚СњР В РІР‚РЋinally the micro-controller writes serially the state of all 40 keyboard TheР В РІР‚СњР вЂ™Р’В¬ontroller program translates the 127 possible AT key codes into spectrum keyboard columnР В РІР‚СњР вЂ™Р’В«its using a look-up table to map one to the other. Is handled by the spectrum so no need to use it on the keyboard end. Simplified key mode where no extended codes are used which makes life easier.Р В РІР‚СњР В РІР‚С›lso the key auto-repeat is disabled. Keyboard is put into the mode 'scan code set 3', which is a The Atmel micro-controller initializes and talks to the keyboard. The design has only two major components, an Amtel AVR ATtiny45 micro-controller (MCU)Р В РІР‚СњР В РІР‚С›nd a XC9572 Xilinx complex programmable logic device (CPLD). Source code (assembler) - AVR studio 4.11 Spectrum databus when a read of the keyboard is made for the row of theР В РІР‚СњР вЂ™Р’В¬orresponding high-address bit. Keycode, turning it into a 5 bit 'row value' and putting it on the So to emulate how the original works, it's just a case of reading in an AT A very cheap, cheerful andР В РІР‚СњР вЂ™Р’В®ffective way of implementing a 40 key keyboard, 8 address lines x 5 Input bit, which was pulled high by a 10k resistor, to the low address The pressed key connected, via a diode, the ULA's keyboard Plus a BBC news story about the beastie HowР В РІР‚СњР В РІР‚РЋor anyone unfamiliar with the Spectrum the keyboard rows were read byР В РІР‚СњР В РІР‚С› z80 'in' op-code with one or more of the high address lines, A8 to A15,Р В РІР‚СњР вЂ™Р’В«eing pulled low and the 5 column bits, D0-D4, being read from the

So what exactly is a zx-spectrum ? Well here's almost everything youР В РІР‚СњР вЂ™Р’В¬ould want to know about this old 8 bit system from the 80's can be found but I did have lots of AT keyboards about the The only problem was the membrane keyboard was In digging out an old 8 bit ZX-Spectrum and really really wanting It all started when I came across an old Timer 2068. Welcome to yet another yet another Sinclair Spectrum keyboard

#SINCLAIR ZX SPECTRUM KEYBOARD PC#

Yet Another Sinclair Spectrum AT keyboard interface Yet Another ZX-Spectrum AT Keyboard Interface ( YAZSAKI ? ) Adding a PC compatible AT keyboard to a zx-spectrum

Sinclair zx spectrum keyboard