Search found 1527 matches

by Pito
Fri Oct 20, 2017 8:28 pm
Forum: Custom design boards
Topic: CPLD Fun Board (Arduino STM32 + Altera CPLD)
Replies: 12
Views: 106

Re: CPLD Fun Board (Arduino STM32 + Altera CPLD)

The large number of I/O pins available in the Altera programmable devices make them ideal for implementing microcontroller I/O expansion. For example, with 500 I/O pins, you can implement 62 units of 8 bit ports.
:)
by Pito
Fri Oct 20, 2017 8:00 pm
Forum: Custom design boards
Topic: Alternative BluePill sized F4
Replies: 15
Views: 236

Re: Alternative BluePill sized F4

The problem with the original design is not the power dissipated itself, but the package type which has got a large thermal resistance so it will smoke at Iout >200mA. A sot-223 or sot-89 or dpack is a better choice, but still the power must be dissipated somewhere. If you chase a small size and lar...
by Pito
Fri Oct 20, 2017 7:35 pm
Forum: Custom design boards
Topic: CPLD Fun Board (Arduino STM32 + Altera CPLD)
Replies: 12
Views: 106

Re: CPLD Fun Board (Arduino STM32 + Altera CPLD)

Mouser lists the EPM570T100 from 14.13 Euro to 31.20 Euro excl. VAT single quantity.. :?
by Pito
Fri Oct 20, 2017 12:12 pm
Forum: Custom design boards
Topic: CPLD Fun Board (Arduino STM32 + Altera CPLD)
Replies: 12
Views: 106

Re: CPLD Fun Board (Arduino STM32 + Altera CPLD)

Nice clean design! Great! The only possible risk with your design is the smaller cpld is small, and the larger is expensive.. An "SPI" or "I2C" module will most probably not fit into the smaller one, but the simplest interface to the stm32 could be done by serial shift in/out. For example 32bit may ...
by Pito
Fri Oct 20, 2017 8:08 am
Forum: Off topic
Topic: NuttX on a BluePill
Replies: 53
Views: 1187

Re: NuttX on a BluePill

@Alan: does the NuttX support hotswapping of the Sdcard when the Card Detect signal is available on the socket? Like mount/umount -> hotswap -> mount.. Here without Card Detect signal (I do not have the signal on my socket available). nsh> mount -t vfat /dev/mmcsd0 /sdcard nsh> ls -l /sdcard /sdcard...
by Pito
Sun Oct 15, 2017 12:26 pm
Forum: Custom design boards
Topic: Alternative BluePill sized F4
Replies: 15
Views: 236

Re: Alternative BluePill sized F4

indeed good idea :) Do use a larger package with Vdd regulator (ie SOT-223 or Dpack - a package with a heatsink fin) - with large copper around/beneath the heatsink fin. Use a lot of vias to thermally connect the top/bottom copper. Read the chapter 10.1. carefully: http://www.ti.com/lit/ds/symlink/...
by Pito
Sun Oct 15, 2017 12:00 pm
Forum: Custom design boards
Topic: Alternative BluePill sized F4
Replies: 15
Views: 236

Re: Alternative BluePill sized F4

Heat around the voltage regulators. You have got a large gnd plane beneath them, but you do not have any vias for a thermal connection to that plane (the heatsink). Calculate the temperature of the Vdd chip (look for the topic I posted few weeks back). That sot23 package will smoke with 5V input and...
by Pito
Sun Oct 15, 2017 11:47 am
Forum: Custom design boards
Topic: Alternative BluePill sized F4
Replies: 15
Views: 236

Re: Alternative BluePill sized F4

1. use an 800mA voltage regulator for Vdd
2. do use more vias (heat, grounding)
3. wait on stm32H743/753 in 100pin flatpack
by Pito
Thu Oct 12, 2017 11:33 am
Forum: General discussion
Topic: Power LED questions
Replies: 10
Views: 230

Re: Power LED questions

The aprox. current taken by an LED is following (3.3V power voltage, R is the series resistor): 1. Red LED I = (3.3V - 1.7V) / R 2. Yellow, Green LED I = (3.3V - 2.0V) / R 3. Blue, White LED I = (3.3V - 3.0V) / R Example: Green LED and 500ohm resistor I = (3.3V - 2.0V) / 500 = 2.6mA From my measurem...
by Pito
Wed Oct 11, 2017 2:40 pm
Forum: General discussion
Topic: [SOLVED] pin state Hi-Z (floating)
Replies: 2
Views: 83

Re: pin state Hi-Z (floating)

Set the pin to INPUT:

Code: Select all

pinMode(PC7, INPUT);