Connect Shield Documentation Questions | Telit Cinterion IoT Developer Community
October 2, 2019 - 6:24pm, 2928 views
Hi, I've been using a Cinterion Connect Shield with ELS61 in standalone mode (USB to my laptop). Able to connect, ping, etc. Now I want to connect the Shield as a peripheral to my Nordic nRF52840-DK board. I downloaded and reviewed the documentation for both boards to make sure I power the Shield correctly and connect the Rx and Tx lines correctly. The Shield document from the Gemalto website is "connect_shield_ug_v02.pdf".
1. Table 1 on page 9 shows that Arduino TX is connected to Modem RxD0, and Arduino RX is connected to Modem TxD0. But the Shield schematic on pages 16 and 17 shows that Arduino TX is connected to Modem TXD0 (via TX_5V and TXD0_1V8), and Arduino RX is connected to Modem RXD0 (via RX_5V and RXD0_1V8). In other words, the table says they're swapped but the schematic says they're straight through. Which is correct ?
2. I'm having trouble understanding the relationship between the 5V and 3.3V supply inputs and the IOREF input. Does the Shield require both 5V and 3.3V power, or will 5V alone be adequate ? If it does require 3.3V, will 3.0V be adequate (the Nordic DK supplies 3.0V, not 3.3V). And am I supposed to tie IOREF to one of the supply inputs ?