Electrical – Intel 8052 (and friends) minimum set up

ftdiintelmicrocontroller

I recently got a batch of old microcontrollers (8052 and Z8671) and I just want to get a minimum working set up for them.

Since these microcontrollers already have most everything baked into them (BASIC, RAM, ROM, Serial Ports), it seems like it'd be a simple matter of plugging them in to an FTDI chip and going about myself.

Looking at the Intel 8052 datasheet, it seems like all I need is a power source, crystal oscillator, and a serial port. Since the FTDI FT232RL is a very common and readily accessible chip, I'm using that for both power and serial I/O.

Here is what I'm using as a schematic.

With all that in place, and trying to use both minicom and picocom, I get no response from the chip at all.

What is it that I'm missing? I've tried using a similar set up for the Z8671 and haven't gotten a response as well.

For reference, here is the pinout of the 8052

Best Answer

Since these microcontrollers already have most everything baked into them (BASIC, RAM, ROM, Serial Ports)

What makes you think that these microcontrollers have BASIC built in?

There was one somewhat rare version of the 8052 that had a BASIC interpreter built in. If you have one of these, it will be clearly marked as a "P8052AH-BASIC", like this one:

These parts were neither standard nor common. The ROM in most other 8052s will contain an application-specific program that's unlikely to be useful to you.

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Electronic – arduino – Serial newbie: why can’t I just hook the wires up

You can definitely transmit data using just TX & GND.

Firstly, you want to hook up the ATtiny85 TX line to the FTDI RX line (yellow on the TTL-232R). Make sure that the USB adapter can handle 5V - I'm fairly sure even the 3.3V TTL-232R is 5V tolerant.

According to the example page for SoftwareSerial, you need to set the direction of the TX & RX lines in your setup function:

// include the SoftwareSerial library so you can use its functions:
#include <SoftwareSerial.h>

#define rxPin 2
#define txPin 3
#define ledPin 13

// set up a new serial port
SoftwareSerial mySerial =  SoftwareSerial(rxPin, txPin);
byte pinState = 0;

void setup()  {
  // define pin modes for tx, rx, led pins:
  pinMode(rxPin, INPUT);
  pinMode(txPin, OUTPUT);
  pinMode(ledPin, OUTPUT);
  // set the data rate for the SoftwareSerial port
  mySerial.begin(9600);
}

The baudrate will be 4800 in your case. The SoftwareSerial library doesn't seem to support CTS & RTS, so just make sure you aren't using them on the host software.

Check out the reference page for more details, where they talk about some potential timing issues which may be exacerbated if you're running at 1MHz using the internal oscillator on the tiny.

Electronic – AVR external crystal not working with UART

double check the following things:

is your baud rate calculation/register setting correct
does your crystal support the selected baud rate (is the baudrate error below the critical threshold)
is your F_CPU setting correct (calculation of baud rate register value may depend on this)
have you correctly set your fuses to use the crystal
have you mixed up RX-TX line connections (look at my comment above)

Best Answer

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Electronic – arduino – Serial newbie: why can’t I just hook the wires up

Electronic – AVR external crystal not working with UART

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