I connect i2c signals as tri1 because of pull-up. I want to see i2c signals as high-z, but assertion is failed because of tri1. Know someone who can answer?
You can convert the strength into a string, and do a string compare
($sformatf("%v",SDA) == "Pul")
This is true when the signal is in the passive pullup state.
Related
I need to read temperature data with using MAX31865 SPI communication. First of all, I tried to read 4 byte data:
import machine
import ubinascii
spi = machine.SPI(1, baudrate=5000000, polarity=0, phase=0)
#baudrate controls the speed of the clock line in hertz.
#polarity controls the polarity of the clock line, i.e. if it's idle at a low or high level.
#phase controls the phase of the clock line, i.e. when data is read and written during a clock cycle
cs = machine.Pin(15, machine.Pin.OUT)
cs.off()
cs.on()
data = spi.read(4)
cs.off()
print(ubinascii.hexlify(data))
I tried many times with different codes but result is always similar b'00000000'.
I am using ESP32 WROOM.
I used this pins:
ESP32 : D12 - D14 - 3V3 - GND - D15
Max31865: SDO - CLK - VIN - GND - CS
I am new on micropython and esp32.
I don't know what should I do. Is there any suggestions , recommended tutorials or idea?
Short answer: see if you can use CircuitPython and its drivers for MAX31865.
Long answer: a bunch of stuff. I suspect you've been following the Adafruit tutorial for MAX31855, but its SPI interface is very different from the MAX31865.
Your SPI connection is missing the SDI pin. You have to connect it, as communication is bidirectional. Also, I suggest using the default SPI pinout on ESP32 side as described in the micropython documetation for ESP32.
The SPI startup looks to be missing stuff. Looking at the SPI documentation a call to machine.SPI() requires that you assign values to arguments sck, mosi, miso. Those would probably be the pins on ESP32 side where you've connected SCLK, SDI, SDO on MAX31865 (note mosi means "master out, slave in" and miso is "master in, slave out").
The chip select signal on the MAX is inverted (that's what the line above CS input in the datasheet means). You have to set it low to activate the chip and high to disable it.
You can't just read data out of the chip, it has a protocol you must follow. First you have to request a temperature-to-resistance conversion from the chip. The datasheet for your chip explains how to do that, the relevant info starts on page 13 (it's a bit difficult to read for a beginner, but try anyway as it's the authoritative source of information for this chip). On a high level, it works like this:
Write to Configuration register a value which initiates the conversion.
Wait for the conversion to complete.
Read from the RTD (Resistance-To-Digital) registers to get the conversion result.
Calculate the temperature value from the conversion result.
The code might be closer to this (not tested, and very likely to not work off the bat - but it should convey the idea):
import ubinascii, time
from machine import Pin, SPI
cs = Pin(15, Pin.OUT)
# Assuming you've rewired according to default SPI pinout
spi = machine.SPI(1, baudrate=100000, polarity=0, phase=0, sck=Pin(14), mosi=Pin(13), miso=Pin(12))
# Enable chip
cs.off()
# Prime a 1-shot read by writing 0x40 to Configration register 0x00
spi.write(b'\x00\x40')
# Wait for conversion to complete (up to 66 ms)
time.sleep_ms(100)
# Select the RTD MSBs register (0x01) and read 1 byte from it
spi.write(b'\x01')
msb = spi.read(1)
# Select the RTD LSBs register (0x02) and read 1 byte from it
spi.write(b'\x02')
lsb = spi.read(1)
# Disable chip
cs.on()
# Join the 2 bytes
result = msb * 256 + lsb
print(ubinascii.hexlify(result))
Convert result to temperature according to section "Converting RTD Data Register
Values to Temperature" in datasheet.
Side note 1: here spi = machine.SPI(1, baudrate=5000000, polarity=0, phase=0) you've configured a baud rate of 5MHz which is the maximum for this chip. Depending on how you've connected your devices, it may not work. The SPI protocol is synchronous and driven by master device, so you can set any baud rate you want. Start with a much, much lower value, maybe 100KHz or so. Increase this after you've figured out how to talk to the chip.
Side note 2: if you want your conversion result faster than the 100ms sleep in my code, connect the DRDY line from MAX to ESP32 and wait for it to go low. This means the conversion is finished and you can read out the result immediately.
Im attempting to use the Xilinx uartlite 2.0 IP with an AXI4-lite interface to transmit a byte without a microblaze processor. Unfortunately, all the ready signals remain low after I set the data and valid signals and the tx signal never transmits.
I've included my simulation results. any ideas?
For posterity, Had to invert the reset and ensure all the inputs were initialized. Thank you for the helpful comments. I've attached a working simulation
I connect PORTC.3 with switch to 5v. in my code I do some thing in conditional block "if(PORTC.3)".in proteus I change state of switch but every time PORTC.3 is 0! what does event occur?
thanks...
You will need to query the PIN register, specifically PINC.3 for you. Each port has one of these registers and it stores the input data of the pin.
Make sure your pins are set as input at the Data-Direction Register (DDR), in your case DDRC and you will need to set them low (logic 0) for them to be configured as an input.
Is there a way to tell the simulator (I'm using Modelsim) to pull a signal to weak 'H' when it's not being driven by either bidirectional interface?
For example if I have an I2C signal I2C_SDA that is declared as an inout from 2 modules. One is my actual UUT and the other is a testbench. Both have statements like this:
io_i2c_sda <= r_I2C_DATA when r_I2C_DATA_EN = '1' else 'Z';
So both ends are tri-stated. This works fine in simulation, except that the line is BLUE ('Z') all the time that neither end is transmitting. How can I pull-up this line to a 'H' in the code when neither end is transmitting?
For VHDL, it should be possible to simply add an extra driver to the signal (which has to be of std_logic type), with the constant value 'H'. In Verilog one would use a simple '1' driver and the net type wand for wired and. 'H' specifically means a weak high driver, so it will be overridden by the low drivers.
Is it possible to query serial port tx (send) pin status if it is active or not ?
For example when issuin break command (SetCommBreak) tx pin is set to active (low). I'd like to know when it is active or not. Thanks.
No. (at least not likely)
If you are using the "16550" family of UARTs, then I am confident that you can not query the serial port tx pin status. Of course, if you are using some new version or other UART family, maybe.
You can assume that the TX pin is in the SPACE state ('0', +Volts) whilst performing SetCommBreak(), but I suspect that is not enough for you.
If you are look to debug your code to know if a break occurred, you can short pins 2 & 3 on a 9-pin D-sub, thus loop backing the transmit to the receive. A paper clip will do. Your receive code would detect the incoming BREAK. Shorting to the incorrect pin does not cause a lasting problem with a conforming serial port, but be careful. Try this first with simple data, before testing BREAK condition.
If you have a "16550"-like UART.
You can put the UART into loop-back mode and see if you receiving you own outgoing BREAK signal. Its somewhat complicated in current PCs. Other UART type may support loop-back.