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• too complex setup of dip switches

  Alvaro Barcellos • 09/25/2023 at 21:30 • 0 comments

  Too complex setup and  sensible to wrong selects at dip switches. Doing a review.
  

• Still waiting

  Alvaro Barcellos • 02/02/2023 at 13:30 • 0 comments

  Still waiting components arrive.

  Going to make a prototype for 64kb FLASH or EEPROMS, without high voltage operation ( 12.5V erase and 14.3V program), with dual serial bus, for address with three 74hc595 and for data with a 74hc595 and a 74hc165.

  todo: support for high voltages, also SPI and I2C FLASH chips.

• updates

  Alvaro Barcellos • 09/14/2022 at 14:25 • 0 comments

  Done small changes:

  No more choice to use high address A16-A23, all bits goes for address A0-A23 by the shift registers.
  

  Support for A27E257 eeprom 32kx8bits, changed dip-switches setup, as pin 1 is VPP, 12.75V to program, or VPP2, 14V for erase, and pin 28 is VCC.

  New schematics v03.

  Circuits for VPP and VPP2 not included.
  

• software redux

  Alvaro Barcellos • 09/09/2022 at 15:03 • 0 comments

  the software will be based on:

  (this list could grow :)

  https://github.com/beneater/eeprom-programmer
  

  https://github.com/daveho/eeprog
  

  https://github.com/TomNisbet/TommyPROM
  

• reference pinout

  Alvaro Barcellos • 09/03/2022 at 15:19 • 0 comments

  As reference pinout for ZIF socket, prefer AT27C040:

  Considering the first 8 pins ( 1, 2, 3, 4, 37, 38, 39, 40) reserved for I2C and SPI, then changes are:
  

  ZIF	REF	A	B	NC
  5	1	VPP	A18	NC
  7	3	A15	A14	VPP
  35	31	A18	WE	NC
  34	30	A17	VCC	NC
  33	29	A14	WE	NC
  32	28	A13	VCC	NC
  29	25	A11	WE	X
  28	24	OE	VPP	X
  20	16	GND	GND	GND

  PS. NC for not connected and X for must be, GND included for mark.

  the schematics altered to comply.

  dip switch 01 and 02 for eeproms:

  to review:
  

  AT28C16, (01 ON: S6, S8, S9), (02 ON: S3)
  AT28C64, (01 ON: S2, S4, S7, S9), (02 ON: S3)
  AT28C256, (01 ON: S2, S4, S7, S9), (02 ON: S4)**
  SST39SF040, (01 ON: S1, S3, S5, S7, S9), (02 ON: S3)
  M27C512, (01 ON: S2, S3, S5, S7, S10), (02 ON: S3)
  W27E257 to review
  AT24CXXX ALL OFF.

  
  

  update:
  

  for W27E257  pin 1 is VPP and pin 28 is VCC
  

• serial pins

  Alvaro Barcellos • 09/02/2022 at 22:06 • 0 comments

  Top 8 pins
  

  The top 8 pins pins-outs of zero-insertion-force (ZIF) socket, are reserved for I2C and SPI, : with follow setup.
  
  
  

  SPI	I2C	PIN		PIN	I2C	SPI
  /CS	S0	1		40	VCC	VCC
  SO	S1	2		39	WR	/HOLD
  /WP	S2	3		38	SCL	MSCK
  GND	GND	4		37	SDA	MOSI

  OBS.
  

  pull-ups 4k7 resistors at (S1, S2, SDA, SCL, WR) and pull-down at S0.
  

  I2C or SPI must be select for use, or go in tri-state.

  
  

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