Does anybody make an IC that takes I2C command and outputs duty cycle (PWM)? I need to control bunch of TECs from CPU and I2C->PWM seems the most efficient (and smallest) way to do it. Any suggestion will be appreciated. Thanks Michael
I2C to PWM IC
Started by ●June 26, 2015
Reply by ●June 26, 20152015-06-26
On Friday, June 26, 2015 at 2:04:44 PM UTC+2, Michael wrote:> Does anybody make an IC that takes I2C command and outputs duty cycle (PWM)? > I need to control bunch of TECs from CPU and I2C->PWM seems the most efficient (and smallest) way to do it. > Any suggestion will be appreciated. > Thanks > MichaelBuy the cheapest microcontroller you can find For example the EFM8BB1, so less that 0.3USD and with a lot of nice features beyond that basic I2C function Cheers Klaus
Reply by ●June 26, 20152015-06-26
On Fri, 26 Jun 2015 05:04:40 -0700 (PDT), Michael <mk617435@gmail.com> wrote:>Does anybody make an IC that takes I2C command and outputs duty cycle (PWM)? >I need to control bunch of TECs from CPU and I2C->PWM seems the most efficient (and smallest) way to do it. >Any suggestion will be appreciated. >Thanks >MichaelPhilips LED controller? Has PWM. Cheers
Reply by ●June 26, 20152015-06-26
On Friday, June 26, 2015 at 8:16:03 AM UTC-4, Martin Riddle wrote:> On Fri, 26 Jun 2015 05:04:40 -0700 (PDT), Michael <mk617435@gmail.com> > wrote: > > >Does anybody make an IC that takes I2C command and outputs duty cycle (PWM)? > >I need to control bunch of TECs from CPU and I2C->PWM seems the most efficient (and smallest) way to do it. > >Any suggestion will be appreciated. > >Thanks > >Michael > > Philips LED controller? Has PWM.> > CheersI saw NXP PCA953X series, thought there would be something newer (less likely be EOL-ed in 5-7 years. :o( Thanks
Reply by ●June 26, 20152015-06-26
On Fri, 26 Jun 2015 05:14:14 -0700, Klaus Kragelund wrote:> On Friday, June 26, 2015 at 2:04:44 PM UTC+2, Michael wrote: >> Does anybody make an IC that takes I2C command and outputs duty cycle >> (PWM)? >> I need to control bunch of TECs from CPU and I2C->PWM seems the most >> efficient (and smallest) way to do it. >> Any suggestion will be appreciated. >> Thanks Michael > > Buy the cheapest microcontroller you can find > > For example the EFM8BB1, so less that 0.3USD and with a lot of nice > features beyond that basic I2C functionThe CY8C4013SXI has I2C built in. And a 32-bit core, to boot. -- Tim Wescott Wescott Design Services http://www.wescottdesign.com
Reply by ●June 26, 20152015-06-26
On Friday, June 26, 2015 at 8:04:44 AM UTC-4, Michael wrote:> Does anybody make an IC that takes I2C command and outputs duty cycle (PWM)? > I need to control bunch of TECs from CPU and I2C->PWM seems the most efficient (and smallest) way to do it. > Any suggestion will be appreciated. > Thanks > MichaelT How do people control temperature (TEC or heater) with s/w? Wouldn't serial bus be more efficient than PWM line (especially if one has bunch of heaters/TECs in the system and I2C bus is present everywhere)?
Reply by ●June 27, 20152015-06-27
On Fri, 26 Jun 2015 13:10:29 -0700 (PDT), Michael <mk617435@gmail.com> wrote:>On Friday, June 26, 2015 at 8:04:44 AM UTC-4, Michael wrote: >> Does anybody make an IC that takes I2C command and outputs duty cycle (PWM)? >> I need to control bunch of TECs from CPU and I2C->PWM seems the most efficient (and smallest) way to do it. >> Any suggestion will be appreciated. >> Thanks >> Michael > >T >How do people control temperature (TEC or heater) with s/w? Wouldn't serial bus be more efficient than PWM line (especially if one has bunch of heaters/TECs in the system and I2C bus is present everywhere)?I2C is nice for communication within a PCB, but for any real distances (a few meters or more) this kind of single ended TTL communication is going to have troubles. For a system spanning a few meters, some RS-485/CANbus differential communication would be useful, but then each load would need to have its own PWM generator and you would need a way to assign addresses to each node. A DIP switch for address assignment is not the most reliable method. My suggestion is that if the number of independently controlled loads is small (less than half a dozen), go for a microcontroller with a sufficient number of PWM channels and use optocouplers on each channel if necessarily.
Reply by ●June 27, 20152015-06-27
On 6/26/2015 1:50 PM, Tim Wescott wrote:> On Fri, 26 Jun 2015 05:14:14 -0700, Klaus Kragelund wrote: > >> On Friday, June 26, 2015 at 2:04:44 PM UTC+2, Michael wrote: >>> Does anybody make an IC that takes I2C command and outputs duty cycle >>> (PWM)? >>> I need to control bunch of TECs from CPU and I2C->PWM seems the most >>> efficient (and smallest) way to do it. >>> Any suggestion will be appreciated. >>> Thanks Michael >> >> Buy the cheapest microcontroller you can find >> >> For example the EFM8BB1, so less that 0.3USD and with a lot of nice >> features beyond that basic I2C function > > The CY8C4013SXI has I2C built in. And a 32-bit core, to boot. >The 8-pin SOIC version (CY8C4013SXI-400) is only 61 cents in single quantity from Mouser.
Reply by ●June 27, 20152015-06-27
On Saturday, June 27, 2015 at 5:54:25 AM UTC-4, upsid...@downunder.com wrote:> On Fri, 26 Jun 2015 13:10:29 -0700 (PDT), Michael > wrote: > > >On Friday, June 26, 2015 at 8:04:44 AM UTC-4, Michael wrote: > >> Does anybody make an IC that takes I2C command and outputs duty cycle (PWM)? > >> I need to control bunch of TECs from CPU and I2C->PWM seems the most efficient (and smallest) way to do it. > >> Any suggestion will be appreciated. > >> Thanks > >> Michael > > > >T > >How do people control temperature (TEC or heater) with s/w? Wouldn't serial bus be more efficient than PWM line (especially if one has bunch of heaters/TECs in the system and I2C bus is present everywhere)? > > I2C is nice for communication within a PCB, but for any real distances > (a few meters or more) this kind of single ended TTL communication is > going to have troubles. > > For a system spanning a few meters, some RS-485/CANbus differential > communication would be useful, but then each load would need to have > its own PWM generator and you would need a way to assign addresses to > each node. A DIP switch for address assignment is not the most > reliable method. > > My suggestion is that if the number of independently controlled loads > is small (less than half a dozen), go for a microcontroller with a > sufficient number of PWM channels and use optocouplers on each channel > if necessarily.The system I am dealing with is small (longest possible connection less than 2'), has at least half a dozen channels. I do not think our CPU has enough (if any) PWM outputs. The "I2V->PWM" decision has been made, I need to come up with solution. Looks like it will be either NXP PCA953X series (potential EOL issue) or DAC and LT TimerBlox chip. Best regards Michael
Reply by ●June 27, 20152015-06-27
On 6/27/2015 8:15 AM, Michael wrote:> On Saturday, June 27, 2015 at 5:54:25 AM UTC-4, upsid...@downunder.com wrote: >> On Fri, 26 Jun 2015 13:10:29 -0700 (PDT), Michael >> wrote: >> >>> On Friday, June 26, 2015 at 8:04:44 AM UTC-4, Michael wrote: >>>> Does anybody make an IC that takes I2C command and outputs duty cycle (PWM)? >>>> I need to control bunch of TECs from CPU and I2C->PWM seems the most efficient (and smallest) way to do it. >>>> Any suggestion will be appreciated. >>>> Thanks >>>> Michael >>> >>> T >>> How do people control temperature (TEC or heater) with s/w? Wouldn't serial bus be more efficient than PWM line (especially if one has bunch of heaters/TECs in the system and I2C bus is present everywhere)? >> >> I2C is nice for communication within a PCB, but for any real distances >> (a few meters or more) this kind of single ended TTL communication is >> going to have troubles. >> >> For a system spanning a few meters, some RS-485/CANbus differential >> communication would be useful, but then each load would need to have >> its own PWM generator and you would need a way to assign addresses to >> each node. A DIP switch for address assignment is not the most >> reliable method. >> >> My suggestion is that if the number of independently controlled loads >> is small (less than half a dozen), go for a microcontroller with a >> sufficient number of PWM channels and use optocouplers on each channel >> if necessarily. > > The system I am dealing with is small (longest possible connection less than 2'), has at least half a dozen channels. I do not think our CPU has enough (if any) PWM outputs. > The "I2V->PWM" decision has been made, I need to come up with solution. > Looks like it will be either NXP PCA953X series (potential EOL issue) or DAC and LT TimerBlox chip.Does it make sense to use another inexpensive MCU? MCUs come in all shapes and sizes. As such they are the perfect peripheral chip in many respects. The only downside is needing to program them in manufacturing. -- Rick
