STM8SJ001J3: a Low-Cost Alternative to the ATtiny85

A project log for eForth for cheap STM8S gadgets

Turn cheap stuff from AliExpress into interactive development kits!

Thomas 08/12/2017 at 14:311 Comment

ST offers a new STM8S device: the STM8S001J3 in an SO8N package. It's more powerful than the ATtiny85: same Flash, double the RAM, less EEPROM, better peripherals (ADC, 1x8bit+2x16bit timers, UART, I2C and half an SPI), and at a price of $0.20 it's much cheaper than the ATtiny85. It's even cheaper than the ATtiny13!

It has another advantage: there is an interactive (untethered) Forth for it! The dataasheet is very similar to that of the STM8S003F3P6, and I hope to receive samples soon. There is a new Wiki page with a feature comparison of different Low-Density STM8 devices: STM8S Low Density Devices. The bottom line is: regardless of the pin count there aren't many differences!

One could argue that it has one pin less to play with (Vcap), but it turns out that my guess that NRST (reset) isn't needed for in-circuit-programming, and on the ATtiny85 side working without the RESET/dW feature isn't really fun. An untethered Forth for the ATtiny85 could settle the score but I couldn't find one.

The reason for the somewhat confusing list of pin properties is that multiple GPIOs are bonded to a pin (with the exception of pin 6). When GPIOs are used in parallel, pin8 can drive up to 80mA within the spec of the device!

For most applications the STM8003F3P6 is a better choice ($0.24@10pcs), but SO8N is so much easier to solder that it ranks high in the gadget rating ;-)


jaromir.sukuba wrote 08/13/2017 at 07:10 point

This IC actually has the STM8S003 chip bonded to SOIC-8 frame. The same chip, just watch out for pins conflict, as multiple chip pads are shorted-bonded to single pin.

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