| Electronics > Projects, Designs, and Technical Stuff |
| Small and cheap MCU with DAC |
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| Wimberleytech:
--- Quote from: nick_d on December 22, 2018, 12:26:04 am ---So Daddy :) Is it true that the cheaper family members omit the DAC, this seems to be so based on the different posts here but I did not do a thorough survey. --- End quote --- At the time, it was all about die size...getting the cost down. Same with the ADC. Had to go with an 8-bit to save area. --- Quote ---Also, why choose 8051, the memory model seems a bit unfriendly to my modern C-oriented eye but perhaps there are good reasons for this? Or is it due to commercial reasons such as compatibility, licensing, availability of an in-house 1T 8051 core? --- End quote --- Good question. You may not like the answer. We knew of a good core at a good price so we bought it and ultimately bought the group that made the core. Simple as that. --- Quote ---Do you design the core or is it more of a matter of integrating IP blocks via a standard bus structure? --- End quote --- Totally custom from the bottom up. --- Quote ---Do you use a HDL, such as Verilog or VHDL? What about simulation, are gate level and transistor level sims done before masks are ordered? Do you use expensive proprietary layout and routing tools? --- End quote --- Verilog. Syopsys and Cadence tools. A very refined methodology to ensure accuracy. In the later days, we did top-level simulations only to ensure blocks were connected properly (pch bias current to nch mirror...stuff like that) We were taping out a new core every four months with heavy reuse. Virtually all of the products are still selling...18 years later. |
| Unixon:
BTW, why so many microcontrollers that have a built-in ADC consisting of a DAC and a comparator circuit don't offer a buffered output from this internal DAC? |
| Wimberleytech:
--- Quote from: Unixon on December 22, 2018, 02:31:20 pm ---BTW, why so many microcontrollers that have a built-in ADC consisting of a DAC and a comparator circuit don't offer a buffered output from this internal DAC? --- End quote --- I would say that most DACs used in SAR ADCs are charge-scaling. These do not work as static DACs. The 12-bit ADC on the early Silabs MCUs is a combination voltage-scaling/charge-scaling DAC. The voltage-scaling portion could be used as a stand-alone DAC. The Silabs 8-bit DAC is totally charge-scaling (for all the early ones). |
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