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I have Sofi SP8 programmer for serial flash memory, with ISP interface for In-System programming. I want try it to read/write memory chip WINBOND 25Q32BVSIG-1246 on board, without desoldering. Manual have notes about this, but it's not clear a few points: if use programmer to provide power supply for the chip (device is power off), how to connect WP and HOLD pins to VCC? ISP interface have VCC pin(#2) that need be connected to VCC pin of chip, so, additionally WP & HOLD pins on chip must be connected to ISP VCC pin too? Should I use some 1 to 3-pins male header adapter for this to split programmer VCC pin to 3 pins?

The other method is to use Power supply from target board (so device should be power on). Which way is preferable?

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Here is ISP programming description from programmer Manual.

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First thing: WP and HOLD should be soft-tied each with a pull-up, as the part also uses these pins as DQ in 4-bit mode. Never hard-tie them.

Second thing: When programming in-system you will need to provide a way to make sure the host doesn't interfere with the SPI pins. Unfortunately, if you just have the host powered off, the host SoC I/O pins will pull down these pins due to their protection diodes. Provide a way to high-Z these pins, by holding reset or some other way, such as a transmission gate, jumper block, etc.

Third thing: You have another option to connect the programmer: a clip directly onto the chip (SOIC clip.) Then you don't need a header.

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  • \$\begingroup\$ Thanks for the advice. For the first point: so I have to use a series resistors between Vcc and WP, HOLD pins, that will provide weak pull-up? Will be 1k fine? Also, about connection: I mean to use SOIC Test Clip, yes. But I need connect 3 flash chip pins (VCC, WP, HOLD) to the second pin of the ISP interface (VCC), so I need to use some sort 1-to-3 wire splitter to split programmers VCC pin between these 3 pins. I mean connect like this. Power supplied by programmer. Is that correct way? \$\endgroup\$
    – fxgreen
    Mar 7, 2020 at 22:23
  • \$\begingroup\$ You don’t need to connect WP and HOLD to the programmer, unless you want to use 4-bit mode. As for your other questions, hard to say not knowing the rest of your system. \$\endgroup\$
    – hacktastical
    Mar 8, 2020 at 0:03
  • \$\begingroup\$ when a 4-bit mode is used in 32-bit MIPS CPU? (in regards to WP and HOLD pins) \$\endgroup\$
    – fxgreen
    Mar 8, 2020 at 11:56

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