AfreshBoard is the new board by Jörgen that's features are:


AfreshBoard/AnnounceMail was sent to to attract developers.

The name comes from that it has lot to do with AFR (Air to Fuel Ratio) measurements.

[you can find more info here - schematic too!]


The board are designed for an LSU sensor but it will work well for the NTK UEGO too with some minor code changes. The Nearst cell temperature measurement could really be left out if a NTK sensor is used.

The Nearst cell is fed with a symmetric pulsetrain and the cell resistance are measured by taking synced samples at the high and low swings.

Initially there was a complex analogue filter that conditioned the Nearst cell temperature signal, it took up quite a bit of board space but was guaranteed to work 'out of the box'. In any case I replaced it with this digital design that will probably work fine after some averaging.

The heater circuit are analog and use a high side valve as this makes it much simpler to keep track of the heater voltage, current, resistance and power. This would not be possible without the dual 15v supply. The heater are not sensitive to low battery voltage.

The Lambda circuit take up about one sixth of the 100X80mm board.

The board also feature ISP programming, two RS232 ports, a 8ch, 12 bit ADC, a 12bit single channel 500ksps ADC, a two channel differential thermocouple input. a HIP 9011 knock sensor signal conditioning circuit, an external eeprom, four inputs for resistive sensors and one voltage output that’s filtered and referenced to external ground.

Inputs for voltage output sensors and timing sensors will be added shortly.

The design was initially meant to be an external logger but it has been integrated in the GenBoard/VerThree project.

AfreshBoard/BillOfMaterials contains the list of materials and people can write their estimated needs there.