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CPU Upgrade Modules

Instead of the default SMT footprint on the main board, the system can be upgraded with a separate CPU upgrade module. The benefit of having the processor on a separate module is, it removes the risk of losing an entire Z20X main board in case the soldering of that single SMT part didn’t go according to plan. The additional benefit is the inherent flexibility of having different type of processor modules using the same system resources.

The processor module is optional and only required in systems where the eZ80 processor is not installed directly on board.

The CPU module pinout follows strictly the eZ80’s pinout for the pins 1 through 100, with one notable exception. The RESET# pin (51) of eZ80 is held permanently low by the module since its pin 51 is connected to ground. Instead, the actual RESET# signal is fed to pin 103 of the module. Hence when the module is installed on the main board it will keep the on-board eZ80 in a permanent reset state, thus taking over completely the system bus.

The CPU module also has an additional provision of +5V power coming to pin 102.

Four pins are connected to external signals with 5V logic (PS/2 interface).

In order to maintain compatibility with the rest of the system, a CPU module that uses a different processor (not eZ80F92/93), should emulate the same pinout and functionality on all pins.

 

 

 

 

 

 

 

 

  1 • A0

  2 • A1

  3 • A2

  4 • A3

  5 • A4

  6 • A5

  7 • +3.3V

  8 • GND

  9 • A6

 10 • A7

 11 • A8

 12 • A9

 13 • A10

 14 • A11

 15 • A12

 16 • A13

 17 • A14

 18 • +3.3V

 19 • GND

 20 • A15

 21 • A16

 22 • A17

 23 • A18

 24 • A19

 25 • A20

 26 • A21

 27 • A22

 28 • A23

 29 • CS0#

 30 • CS1#

 31 • CS2#

 32 • CS3#

 33 • +3.3V

 34 • GND

 35 • D0

 36 • D1

 37 • D2

 38 • D3

 39 • D4

 40 • D5

 41 • D6

 42 • D7

 43 • +3.3V

 44 • GND

 45 • IO#

 46 • MEM#

 47 • RD#

 48 • WR#

 49 • INSTR#

 50 • WAIT#

 51 • GND

 52 • NMI#

 53 • BUSREQ#

 54 • BUSACK#

 55 • HALT#

 56 • +3.3V

 57 • GND

 58 • RTCI_32768

 59 • RTCO_32768

 60 • +3.3V_RTC

 61 • GND

 62 • TMS

 63 • TCK (ZCL)

 64 • TRIGOUT

 65 • TDI (ZDA)

 66 • TDO

 67 • +3.3V

 68 • PD0/TxD0

 69 • PD1/RxD0

 70 • PD2/RTS0#

 71 • PD3/CTS0#

 72 • PD4/DTR0#

 73 • PD5/DSR0#

 74 • PD6/DCD0#

 75 • PD7/RI0#

 76 • PC0/TxD1

 77 • PC1/RxD1

 78 • BACKLIGHT

 79 • TOUCH_IRQ#

 80 • PS2MD (5V)

 81 • PS2MC (5V)

 82 • PS2KD (5V)

 83 • PS2KC (5V)

 84 • GND

 85 • XT1_18MHZ

 86 • XTO_18MHZ

 87 • +3.3V

 88 • PB0/T0IN

 89 • TOUCH#

 90 • PB2

 91 • SCLK

 92 • SD#

 93 • PB5 (FLASH#)

 94 • MISO

 95 • MOSI

 96 • +3.3V

 97 • GND

 98 • SDA

 99 • SCL

100 • FREQ_CPU

101 • unused

102 • +5V

103 • RESET#

104 • unused