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Guild: wafer.space Community
Channel: Information / general / Using gf180mcu_ocd_io in LibreLane
After: 03/31/2026 23:59
Before: 05/01/2026 00:00
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[04/22/2026 06:42] 246tnt
@Tim Edwards BTW, basic testing seem to show that IO library works in silicon 🙂


[04/22/2026 06:53] 246tnt
Changed the channel name: Using gf180mcu_ocd_io in LibreLane


[04/22/2026 12:03] rtimothyedwards_19428
@tnt :  What kind of "basic testing"?


[04/22/2026 12:04] 246tnt
Well, they're fed 3.3v on both Vio and Vcore and they pass data between the inside and the outside of the chip 😅


[04/22/2026 12:04] rtimothyedwards_19428
What chip was that?  I thought I was the only one using my I/O library.


[04/22/2026 12:04] 246tnt
That's the extend of the testing that will be done at the factory until I get my hands on the chips.


[04/22/2026 12:05] 246tnt
We have a version of the tiny tapeout GF 0.2 that uses your library.


[04/22/2026 12:05] rtimothyedwards_19428
Oh, wow, I didn't know that.  Nice!


[04/22/2026 12:07] 246tnt
Hopefully by end of next week I'll be able to make actual delay / rise / fall measurements and IV curves and all that stuff with different Vio and Vcore .


[04/22/2026 12:07] rtimothyedwards_19428
I don't think I ever actually tested operation with Vio at 3.3V.


[04/22/2026 12:08] 246tnt
I simulated that case and it's behaving just fine AFAICT. Pretty much same results as the original GF pads at 3.3v.


[04/22/2026 12:09] 246tnt
Some of your dies should be on their way to you so if you have bonding capability locally you can test those too 🙂 Looking fwd to seeing the 3.3V SRAM results 😁


[04/23/2026 14:16] mithro_
@tnt - The first package of Tiny Tapeout bonded die went out to you today.

{Reactions}
🎉

[04/23/2026 14:21] 246tnt
@Tim 'mithro' Ansell Got a tracking number ? 😅


[04/23/2026 14:23] mithro_
I would be able to get you one if the fedex website wasn't so terrible...


[04/23/2026 14:23] 246tnt
🤣


[04/23/2026 14:23] 246tnt
It's ok, I guess I should eventually get a notification by mail.


[04/23/2026 14:23] 246tnt
Better not share it publically anyway ..


[04/27/2026 15:34] 246tnt
@Tim Edwards Did a bit more testing and they seem to perform just fine at 3.3V    Got rise time of 2 ns and fall time of 1 ns ( not sure of the load, it's a test pcb + scope probe so probably in the 20~30 pF range ). And the output still looked pretty square outputting a 75 MHz clock.   TBH they work better than the sky130 and IHP ones 😅


[04/27/2026 15:55] rtimothyedwards_19428
The sky130 pads are over-designed and the IHP pads are under-designed, so that's not entirely surprising.  Are you planning any tests at 5V?


[04/27/2026 15:58] 246tnt
@Tim Edwards Yes I am. But the breakout I have is unsuitable for 5V test ATM, so I need to wait until I get one where I can set Vio to what I want.


[04/27/2026 16:01] 246tnt
BTW there are diodes between Vcore and Vio, so Vio needs to come up first


[04/27/2026 16:24] rtimothyedwards_19428
I'm not sure if I looked specifically for diodes between the power supplies.  Would there happen to be a forward-biased diode from Vio to Vcore?  That would be a big problem for running the I/O voltage at 5V.


[04/27/2026 16:24] 246tnt
No, it's forward biased from Vcore to Vio.  So must have Vio >= Vcore


[04/27/2026 16:27] rtimothyedwards_19428
In what cell(s)?  A quick check of the netlist for `D` entries shows only diodes between pad and power, and between ground and power.


[04/27/2026 16:27] 246tnt
Ah ... that I haven't searched yet, I can just tell you I see it in the silicon 😅


[04/27/2026 16:28] rtimothyedwards_19428
Probably some indirect path like through a pullup resistor or something.


[04/27/2026 16:28] 246tnt
I was feeding 3.3V to Vcore and I haden't power Vio yet and still the IO were powered through it ...


[04/27/2026 16:29] rtimothyedwards_19428
I'll have to go analyze that one.


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