10:14 <Hammdist> I would like to have stm32 and fpga on the same board, using ft232h. is there any way to get both connected to the same JTAG port or do I need two ft232hs?

10:15 <Hammdist> iow what kind of bus is jtag is it like i2c or like spi?

10:17 <Hammdist> probably relevant https://electronics.stackexchange.com/questions/382372/how-to-connect-multiple-jtag-devices reading now

10:18 <Hammdist> so I guess my question now is does openocd support diaisy chain JTAG?

10:22 <PaulFertser> Hammdist: sure you can chain JTAG devices, that's the whole point.

10:25 <Haohmaru> probably not like SPI because there would have to be a finite number of "chipselect" signals

10:30 <PaulFertser> Haohmaru: some SPI devices can be chained without per-chip signal. So yes, JTAG is kinda like SPI in that regard.

10:32 <Haohmaru> doesn't that count as exotic?

10:33 <PaulFertser> People often chain shift registers and driver them from SPI master.

10:33 <Haohmaru> i do too

10:34 <gamiee> lol I didn't knew it's possible to chain JTAGs lol :D

10:34 <Haohmaru> 74hc595 and 75hc165 (with additional circuitry to make it tristate the output properly)

10:35 <Haohmaru> but i'd think the chipselect is an important thing for SPI, unless with "spi vs i2c" you just mean "synchronous full-duplex vs uhm.. lousy half-duplex"

10:36 <PaulFertser> gamiee: moreover JTAG was designed for cases when you can have several boards and you chain their JTAGs externally to be able to test the whole assembly.

10:36 <PaulFertser> Haohmaru: one common latch signal is enough

10:37 <gamiee> PaulFertser : super coooool! I really didn't knew about this.

10:37 <gamiee> This is good because BL808 is having two cores, and both are exposed in different pins.

10:37 <Haohmaru> oh well, in my head i call this "exotic spi" or "kind-of-similar-to-spi"

10:38 <PaulFertser> And there exists additional test boards e.g. for inserting instead of a DRAM memory stick in the motherboard and then you have a cable to connect it in chain with the CPU and chipset JTAGs and get the whole link tested.

10:39 <Haohmaru> i do have 595 and 165 shift-registers on this board together with proper SPI eeprom and other things, all on the same SPI periph, but the shift-registers (particularly the 165) isn't legally SPI

10:40 <gamiee> wow

10:40 <PaulFertser> Haohmaru: right. I said "kinda like SPI in that regard" (daisy-chaining connecting shift registers)

10:41 <Haohmaru> gamiee, where did you buy that BL808 from? ;P~

10:41 <Haohmaru> there was a time when i wanted to see a price for that.. but it looked like unobtanium

10:42 <gamiee> Haohmaru: I don't have the chips directly (yet). At some point I want to do custom development board for it.

10:43 <Haohmaru> oh wait, this was the one with 3 different cores?

10:44 <gamiee> Haohmaru: BL808 have 1x C906, 1x E907 and 1x E902

10:45 <Haohmaru> yeah this is probably not for me, smells like an "application processor"

10:45 <gamiee> BL606P (which is older and cut-down version of BL808 have those 3 cores as well.)

10:45 <gamiee> Haohmaru: Indeed BL808 is more complex than MCU, but I see it as being middle between MCUs and Linux SoCs.

10:46 <Haohmaru> it does seem to have tasty double precision FPU and some SIMD stuff

10:47 <gamiee> I am working past week heavily with BL606P (working on firmware for PineVox), and so far, it's nice step up from working on MCUs, since there is also mailbox for IPC and some more complex peripherals. But still not that hard as complex Linux SoCs.

10:47 <Haohmaru> how much MHz is that one?

10:48 <Haohmaru> huh, still 480

10:49 <gamiee> honestly, no idea. Would need to checkout datasheet but I am at work :D But C906 (the most powerful CPU in it) can get fast enough to run Linux

10:49 <gamiee> only thing I don't like on BL808 and BL606P is that it uses T-Head cores :D and the E902 core uses CJTAG

10:50 <Haohmaru> no clue what that is

10:51 <Haohmaru> so i see pine64.com have whole boards with these for like 8 bucks, wtf

16:02 <gamiee> Haohmaru: yeah, the chip is super cheap for what it is. Sadly, software support is... messy, but hopefully, I can improve it soon :)

16:02 <gamiee> Plan to do mainline openocd support for that chip as well.

16:03 <Haohmaru> the question is.. is it cheap because it's cheap or for some fishy reasons

16:04 <Haohmaru> at 8bucks i could buy one even if it turns out that i can't do sh*t with it

16:07 <gamiee> Haohmaru: it is cheap because the chip is cheap. I have many of them :)