7 years, 9 months ago.

max voltage level for Rx and Tx:mbed lpc1768

I have an mbed board with LPC 1768. I want to receive serial data from a zigbee adapter which works on 5V. The voltage beween the Rx Tx pin and ground of the adapter is around 4.99 V. Is it safe to connect it directly to the mbed board Rx, Tx.

1 Answer

7 years, 9 months ago.

All digital input pins on the LPC1768 are 5V tolerant (the analog pins (ADC mode) are not). The 3V3 outputs on the LPC1768 should still be able to drive the 5V inputs on the zigbee. So you should be able to connect the 5V side to the 3V3 side. However, to be safe you can add a series resistors between the 5V TX and 3V3 RX pairs, say 1K. If you want to do it 'by the book' you need some logic levelconverters.

Accepted Answer

Thanks Wim

posted by Rijo Thomas 30 Jun 2016