#avr Logs

Aug 29 2019

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05:56 AM Fuchikoma: rue_mohr> how many io do you have for how many buttons? <-- Just enough :) One 1-of-4 switch (2 inputs) and three buttons. I decided that I don't need to interrupt on switch change so that makes things a bit simpler
06:00 AM Fuchikoma: I may go to from UART to 1-wire for the audio module interface to free up an extra pin, but at the moment that doesn't seem necessary
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11:10 AM cehteh: https://www.heise.de/newsticker/meldung/5-Dollar-Entwicklerboard-mit-RISC-V-Sipeed-Longan-Nano-4509949.html
11:10 AM cehteh: woah
11:13 AM Fuchikoma: That's a lot of german
11:16 AM Fuchikoma: https://www.cnx-software.com/2019/08/29/longan-nano-gd32v-risc-v-development-board-comes-with-lcd-display-and-enclosure/
11:16 AM Fuchikoma: For the benefit of anyone else... basically the same article :/
11:16 AM cehteh: nice
11:17 AM cehteh: i think i just order a few :D
11:18 AM Fuchikoma: Can't find a datasheet for this GD32V
11:18 AM cehteh: http://dl.sipeed.com/LONGAN/Nano/DOC/
11:18 AM cehteh: just searching as well :)
11:19 AM Fuchikoma: Aha
11:23 AM cehteh: http://dl.sipeed.com/LONGAN/Nano/Spec/Sipeed%20longan%20nano%20Datasheet%20V1.0.pdf
11:24 AM cehteh: nice peripherials
11:28 AM Fuchikoma: That's what SHE said!
11:28 AM Fuchikoma: 32KB of RAM what the hell are ya gonna do with all that
11:29 AM cehteh: well such a risc-v board was exactly what i was waiting for
11:29 AM Fuchikoma: Does seem like a nice bit of kit
11:30 AM Fuchikoma: USB OTG
11:34 AM cehteh: waah .. 11.53$ shipping ...
11:34 AM Fuchikoma: oof
11:35 AM Fuchikoma: Well you just have to order like five of them to make the shipping worthwhile :D
11:35 AM cehteh: put 4 in the cart, but i tihnk i ask friends if they want some as well maybe we get 10pcs
11:58 AM Fuchikoma: So digging a little deeper; That module uses a 8MHz crystal
11:59 AM Fuchikoma: But the chip itself supports *at least* 54MHz, maybe 108MHz
11:59 AM Fuchikoma: And even Arduino boards run at 16MHz
11:59 AM Fuchikoma: So... what the heck
12:02 PM nohit: what ?
12:02 PM nohit: that is normal
12:06 PM nohit: you feed that 8MHz crystal to a PLL
12:06 PM nohit: and get all the different clocks you need
12:09 PM Fuchikoma: But why 8MHz when it clearly supports 16MHz?
12:24 PM nohit: why would it matter
12:25 PM nohit: you just need a reference
12:26 PM nohit: 8MHz is actaully better since its smaller
12:35 PM Fuchikoma: why would it matter if you have a faster clock?
12:36 PM nohit: i just told you that you feed it into a PLL and get the actual clocks from there
12:37 PM nohit: like that 54MHz
01:54 PM cehteh: Fuchikoma: some attinys can generate 64mhz from the internal 8mhz clock .. use that for a timer (woho 16bit 64mhz PWM) and divide that so you can run the core at 16Mhz without an external crystal
01:55 PM cehteh: iirc modern PC's have only 100mhz crystals or something like that and still run at 4ghz
02:00 PM Fuchikoma: I'm aware of what a PLL is but I still don't see the advantage of an 8MHz input vs a 16MHz input
02:01 PM Fuchikoma: I'm likely wrong but it seems to me the lower the frequency multiplier the better
02:01 PM cehteh: makes no much difference, maybe 8mhz is even cheaper, needs less power
02:02 PM Fuchikoma: mebbe