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11

Projects, Designs, and Technical Stuff / Re: PC74hct4046ap Replacement

« Last post by BrianHG on Today at 02:22:16 am »

Hi, are you saing my current PC74hct4046ap is a little less noise than 74HC4046? If so is the SN74LV4046AN even less noisy?   

HC4046 should be a little less noisy.
LV4046 isn't designed for 5v supply, it's designed for 3.3v supply and below.  (Don't quote me here, double check the data sheet.)

12

Microcontrollers / Re: Routines to convert binary to BCD in C code

« Last post by Nominal Animal on Today at 02:15:52 am »

Is there an actual problem that's trying to be solved here?

Not really.  Binary to decimal conversion is considered "slow" and requiring "surprisingly much" machine-level code, compared to arithmetic operations, so these can be useful in some cases, but that's about it.

Library implementations, especially various printf() implementations, are written for correctness and not for efficiency, so when you work with smaller microcontrollers, especially 8-bit ones (AVRs, PICs, 8051s), a custom implementation can be useful.  More annoyingly, most standard library functions use arbitrary precision arithmetic and dynamic memory allocation during conversion of floating-point numbers.

Even on fully hosted C environments, it turns out that if you read numeric data from text files, the standard C library string-to-number conversions (strtod(), strtol(), scanf() and their variants) become the bottleneck, when you have enough (megabytes) of data.  Then, too, "optimized" conversion functions can reduce the load times to a fraction of what they would be using standard C conversion functions.

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RF, Microwave, Ham Radio / Re: WSJT-X on Pi

« Last post by tatel on Today at 02:10:21 am »

Glad you achieved it. Enjoy.

14

Beginners / Re: Replacing SRAM IC with Flash

« Last post by Nominal Animal on Today at 02:05:13 am »

I noticed LCSC and JLCPCB do not have many parallel SRAM IC's in stock; currently only 7 different models, of which only two are suitable, and cost 30€+.  Ouch.

I thought of pulldown the 4 pins to have initial address bank of 0

Sure.

please check attached initial rough drawing for the whole suggested system.

Displaying the bank number in anything except binary is a bit of a chore.  CD4511 and similar can do 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 using 7 LEDs (7-segment display) based on the four address lines, but would be blank for the last five.  Decoders like 74'138D can decode three address lines into 8 LEDs, so you'd need two of those, and one logic inverter (for the extra bit, a single MOSFET will do).

Hmmm....

The access time of the Sharp LH52256C/CH is 70ns, which corresponds to slightly over 9 clock cycles at 133 MHz.  It seems to me you might be able to use an RP2040 (C2040 at LCSC, about 1€ at LCSC and JLCPCB) to emulate parallel SRAM using PIO via (15+8+3) 26 I/O pins, two pins for I2C (128×32 OLED display), and two pins for buttons – perhaps an I2C slave, shift register, or something.  See various "PicoRAM" projects.

The 26 I/O pins do need (unidirectional) level shifting between 5V (N64) and 3.3V (RP2040) – perhaps four 74LVC4245APW,118 (C6091 at LCSC).

RP2040 uses an external QSPI Flash chip, up to 16 MBytes (Winbond W25Q128JVS is used in examples, C97521 at LCSC; minimum 100,000 erase cycles); some of this would be reserved for code and bootloader, but we're talking a three to five hundred "banks", easy.  And since it has an USB connection, you could transfer the saved states to/from a computer, each 32k long and corresponding to a separate Pak.

The Hardware Design with RP2040 includes a minimal example.  The power section would differ in that you'd use two diodes or a dual common-cathode diode in front of the 3.3V regulator, to select between USB and N64 5V sources.  (Some '1117 series regulators fail short circuit, so I'd suggest carefully selecting which one to use.)  The level translators would be powered from the N64 5V.  You also need a 12 MHz crystal (Abracon ABM8-272-T3, C20625731 at LCSC).  The USB D+ and D- lines need 27.4Ω resistors in series, between RP2040 and the USB connector.  So, in addition to the minimal example schematic (page 25), we'd need the voltage translators, I2C pull-up resistors (two 2.2kΩ, or at least pads for two 0603 resistors), and say a TI TCA6408A (C181499 at LCSC) or TCA9555PWR (C465732 at LCSC) as an I2C expander, providing 8 or 16 additional I/O pins that you could use for buttons or LEDs.

Essentially, the RP2040 would keep a single Pak (32kbytes of RAM) in memory as long as it was powered on, but whenever a button is pressed, copy it to Flash.  (Another option would be to use another PIO to observe the /WR pin, to auto-trigger a save a half a second to second after the last write.)
Additional buttons would be used to select which Pak is currently active.  Since there are so many Paks to choose from, you probably want at least three buttons (next, previous, select), but note that additional modes like "read-only Pak, changes not saved to Flash" and auto-allocating a Pak to a new slot whenever changed, would be easy to implement in software, so at least one more button to select between configuration and Pak is needed.  So, say five buttons.  A TCA6408A provides eight additional I/O pins, perfect for buttons.

going MCU is a no-go for me since i won't be getting the production boards here to my country (Jordan) due to excessive customs charging and the complicated stuff I need to do. All my other products which are being sold now come from PCBway directly to my shipment and fulfillment company (Next Smart Ship) which is linked to my store... then I ship with press of a button.

Ah, okay.

how much bom cost do you expect after this?

I'd expect under 10€ in any case, but that assumes you could get the SRAM chip at Mouser prices (~ 6€ or less) somehow.

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Projects, Designs, and Technical Stuff / Re: PC74hct4046ap Replacement

« Last post by dj_holmes on Today at 01:53:42 am »

Hi, are you saing my current PC74hct4046ap is a little less noise than 74HC4046? If so is the SN74LV4046AN even less noisy?   

16

Manufacturing & Assembly / Re: LPKF Protomat S42: Machine "shock absorber"/"stroke limiter" tuning

« Last post by rsaxvc on Today at 01:53:31 am »

I'm afraid I may not have explained my challenge accurately enough. I'm trying to drill reference holes in the plastic strips the non-camera S42 uses for PCB registration. Once I'm able to do so, I should be able to install a pair of reference pins in the strips, then fit PCB with corresponding holds over the pins, mill one side of a PCB, flip it, and mill the other, then drill and slip a bit of wire through, solder on both ends.

The bit for drilling the reference specified in the manual and software, as a 2.95mm drilling bit I couldn't find on LPKF's website. My machine came with two 38mm 2.95mm drill bits, but they're short enough that the Z-stroke-limiter just barely prevents contact with the bed or reference strips.

You've got me thinking that a longer 2.95mm drill bit is probably what the machine originally came with from LPKF, and I'd like to replace it, but I'd need to know the length required for the right depth. Too shallow and the pins are likely to loosen prematurely, too deep and it might drill fully through the reference strip into the aluminum bed.

I've attached a photo of my machine that I hope shows this better.

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Power/Renewable Energy/EV's / Re: Why are all Vicor PI3 modules suddenly out of stock or obsolete?

« Last post by jbb on Today at 01:50:06 am »

It’s a long shot, but could be clerical error at Digikey end. Suggest you cross your fingers and check with Victor directly.

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Projects, Designs, and Technical Stuff / Re: PC74hct4046ap Replacement

« Last post by BrianHG on Today at 01:47:58 am »

SN74LV4046A This chip has the same pinout. I think its only SMD where I need the pins but I can try and find an adaptor and solder myself. Its its an improvement its definetly worth a try


ok I think I found the dip version SN74LV4046AN

Good old 74HC4046 is still readily available in DIP and SMD.
The only difference with the 74HCT4046 are that the 'digital' inputs low-to-high voltage threshold and the HC variant can be a bit less noisy on it feedback input & PC inputs.

19

FPGA / Re: If Lattice iCE40UltraPlus has DDR primitives like ODDR in Xilinx?

« Last post by BrianHG on Today at 01:31:25 am »

@(posedge clk) for controls, @(negedge clk) for reading back data, though you need to latch that data through a second adjacent @(posedge clk) to sync the data to your master system clock.  Depending on the fpga's speed and clock frequency, it can work just fine as a d-latch to another d-latch with 0 logic in between can potentially run at 200mhz or more.  IE, it would be as if you had a 400mhz primary clock running in sdr mode.  But, how good will your .sdc file be and how good will lattice's IDE handle it.  I know with Altera Quartus, even with their old PLDs, this wouldn't be a problem and the compiler would spit out any timing issues during timing analysis.  Lattice on the other hand???  If you are using Lattice Diamond, they have recently removed .sdc file support for their own custom timing constraints architecture.  I wasn't impressed.

20

Power/Renewable Energy/EV's / Re: Aussie Fast Charger Company Tritium Goes Bust

« Last post by quince on Today at 01:18:31 am »

The green pullback is severe whiplash for these overdone companies I think.
Downturn - Tesla is getting trashed too, laid off 10% or 6,000 staff in California and Texas. Let's just blame the economy, not the Cybertruck fiasco, not the CEO, not the silly expensive products etc.
"Andrew Baglino, the senior vice president of powertrain and energy engineering, said on X that he had made the “difficult decision to move on from Tesla after 18 years”. This a  bad omen.

Tesla's stock is up 25% over the past week, though. The layoff was strategically valid.