HI-35870

The HI-35870 from Holt Integrated Circuits is a silicon gate CMOS device for interfacing a Serial Peripheral Interface (SPI) enabled microcontroller to an ARINC 429 serial bus. It is a drop-in replacement for Holt’s popular HI-3587, with a much improved SPI of 12 MHz.

The device provides one ARINC 429 transmitter with 32 X 32 Transmit FIFO and built-in line driver. Transmit FIFO status can be monitored using the programmable external interrupt pin, or by polling the HI-35870 Status Register. Other features include a programmable option of data or parity in the 32nd bit, and the ability to switch the bit signifiance of ARINC 429 labels. Line driver output pins are available with different values of output resistance to provide flexibility when using external lightning protection circuitry.

The Serial Peripheral Interface minimizes the number of host interface signals and provides a small footprint device that can be interfaced to a wide variety of industry-standard microcontrollers supporting SPI. Alternatively, the SPI signals may be controlled using four general purpose I/O port pins from a microcontroller or custom FPGA. The SPI and all control signals are CMOS and TTL compatible and support 3.3V or 5V operation.

The HI-35870 applies the ARINC 429 protocol to the transmitter. ARINC 429 databus timing comes from a 1 MHz clock input, or an internal counter can derive it from higher clock frequencies having certain fixed values, possibly the external host processor clock.