Dual Voltage 3.3v/5v Ethernet Shield

Hi Guys

I am working on using the Nano with Ethernet shields.

The shield I am using is, like all the other shields I have found, a 3.3v module. I have it working OK with power from the USB, with the Nano supplying the 3.3v.

I now want to use it not powered from the USB. However on the Nano the 3.3v supply is generated by the FDTI USB chip, hence no USB - no 3.3v.

I thought that I was going to have to put in a 5v-3.3v converter. However I have just found these Ethernet modules that work on 5v and 3.3v :- http://www.ebay.co.uk/itm/251202467066?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649

They have an on board 3.3v regulator so you can power them from the Vcc pin, or directly from the 3.3v pin. At about $6 US or £3.60 UK they look a good deal, under $2 more than the shields I am using. I have 2 on order; just have to wait for them to come from HK.

Hopefully this info will be of use to some of you.

AcmeUK:
Hi Guys

I am working on using the Nano with Ethernet shields.

The shield I am using is, like all the other shields I have found, a 3.3v module. I have it working OK with power from the USB, with the Nano supplying the 3.3v.

I now want to use it not powered from the USB. However on the Nano the 3.3v supply is generated by the FDTI USB chip, hence no USB - no 3.3v.

That is not actually true. The FTDI chip gets it's Vcc voltage from the same source as powering the 328P chip, so as long as your are powering the nano from some voltage source the FTDI chip will be powered up even if not plugged into a PC USB port. The big thing to be aware of is the very limited 3.3vdc current capacity of the FTDI's internal 3.3vdc regulator, at something like 50ma max limit before damage to the FTDI can happen. I would think that any Ethernet shield operating at 3.3vdc would require more then 50ma of 3.3vdc to operate, so powering such a shield from the nano's 3.3vdc pin would never be an option no matter how you are powering the nano?

Lefty

I thought that I was going to have to put in a 5v-3.3v converter. However I have just found these Ethernet modules that work on 5v and 3.3v :- http://www.ebay.co.uk/itm/251202467066?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649

They have an on board 3.3v regulator so you can power them from the Vcc pin, or directly from the 3.3v pin. At about $6 US or £3.60 UK they look a good deal, under $2 more than the shields I am using. I have 2 on order; just have to wait for them to come from HK.

Hopefully this info will be of use to some of you.

retrolefty:
That is not actually true. The FTDI chip gets it's Vcc voltage from the same source as powering the 328P chip, so as long as your are powering the nano from some voltage source the FTDI chip will be powered up even if not plugged into a PC USB port.

Hi Lefty

Thanks for your reply. It looks as though you may be right. Looking at the Nano R3 schematic bears out what you say. I will have to get my voltmeter out to verify.

However as you say the FT232R chip is only specefied to supply 50ma on the 3V3OUT pin; so perhaps running the ethernet module from 5v may save me some problems.

Thanks

They have an on board 3.3v regulator so you can power them from the Vcc pin, or directly from the 3.3v pin. At about $6 US or £3.60 UK they look a good deal, under $2 more than the shields I am using. I have 2 on order; just have to wait for them to come from HK.

Those ethernet devices are quite a bit harder to use than the W5100 based ethernet shields. Just so you are aware.

PaulS:
Those ethernet devices are quite a bit harder to use than the W5100 based ethernet shields. Just so you are aware.

Hi Paul

Thanks for the 'heads up'. However I have used a ENC28J60 Shield with a Duemilanove clone.

I am now using the ENC28J60 'mini' shield with a Nano. I use the latest version of the EtherCard library and I have had no problems.

What users need to be aware of is that there are significant differences between the W5100 and the ECN28J60 shields and use the appropriate library and interconnect.