#avr Logs

Oct 16 2019

03:18 AM jmorris: anyone have an example of playing music with PWM and a timer interrupt
03:26 AM cehteh: i mean both pwm and pcm .. use one timer to generate the signal and another one to modulate it
03:33 AM nohit: https://www.adestotech.com/wp-content/uploads/doc1456.pdf
04:31 AM djph: jmorris: basically every sound chip out of the 1980s
06:19 AM elektrinis: anyone tried ATTINY1617 or similar?
06:19 AM elektrinis: these have some fancy peripherals, like nesting
06:19 AM LeoNerd: 3217, yes
06:20 AM LeoNerd: I -have- a 1617 in a bag somewhere but I haven't used it. The 32 version is bigger :)
06:20 AM elektrinis: like, presumably, you can use analog comparator and connect its output to timer input, internally
06:20 AM LeoNerd: Well, more flash
06:20 AM LeoNerd: Yah; that's common to all the 1-series chips
06:20 AM elektrinis: looks like some very nice things could be done, like, DC/DC converter....
06:21 AM elektrinis: a fancier one, current-mode etc
06:21 AM LeoNerd: Yeah; TCD has the feel of an H-bridge driver to it
06:22 AM LeoNerd: with its dead-times
06:24 AM elektrinis: nice app note: Core Independent Brushless DC Fan Control
08:55 AM julius: hi
08:56 AM julius: i read on wikipedia that for the 1-wire bus the pullups depend on the devices attached to it. for example on wikipedia they name 1-2.2k as a usual pullup, but in the ds18b20 temperatur sensor datasheet they give a 4.7k as a example
08:56 AM julius: what happens if you put different devices on the bus, what kind of pullup resistor would you choose?
08:57 AM julius: kind of a theoretical question since i only got one temp sensor on it
08:57 AM twnqx: i wouldn't change the resistor at all
08:58 AM julius: question is, why isnt there a fixed value for the protocol at all?
08:58 AM julius: for the resistor i mean
09:00 AM twnqx: because it depends on your remaining circuitry
09:00 AM damjan: afaik it also depends how long the cables are
09:00 AM twnqx: the stray capacitance from cables, PCB traces, etc causes your signals to degrade
09:01 AM twnqx: so as the capacitance gets higher, you need more current (and thus lower resistance) to overcome it
09:03 AM Fuchikoma: The lower the pullup resistor value, the more power you'll burn through (and possibly overload the device's pin as it tries to sink too much current)
09:04 AM Fuchikoma: Too low a value can prevent the devices from pulling the line low
09:04 AM twnqx: that's the other end of it. so you need to select a value that balances both factors - not too high, not too low.
09:04 AM Fuchikoma: The higher the pullup resistor value, the longer it will take to "charge" the line back up to the higher voltage state, which can fuck up the timings
09:05 AM Fuchikoma: And a really long wire may not be drained fast enough to meet the timing spec
09:06 AM Fuchikoma: And that's before you get into environmental noise considerations; Lone wires are erally good antennas after all
09:06 AM Fuchikoma: s/Lone/Long
09:31 AM cehteh: julius: soemtimes it needs some experimenting, but for the ds1820 you most likely want to provide vcc as well then the pullup isnt very critical, you'll notice when it works/does not work
11:23 AM day__ is now known as day
11:46 PM day__ is now known as day