On their weekend off, a group of coworkers went to a gaming arcade to unwind. They were prepared to feed cash into a kiosk that dispensed gaming credits. Unfortunately, the machine refused to take their money. It was broken and did not have an “out-of-order” sign posted on it.

As a result, after some frustrating time wasted attempting to interface with the faulty machine, the group waited in line at an alternative kiosk that was dispensing gaming credits. Fed up with the wait, some of them left the arcade without spending a single credit. The machine down time translated into a small, but genuine, loss of revenue to the gaming organization. Multiplying that one experience by all the inoperative, revenue-generating machines everywhere, adds up to a significant chunk of lost revenue.

The previous scenario happens frequently, not just with gaming kiosks, but to numerous appliances, including vending machines, coin-operated laundry machines, slot machines at a casino, and more. And a machine doesn’t have to be broken to lose money for its owner, it merely has to be sold out of something someone wants. This happens frequently with understocked vending machines and hotel mini-bars.

Commercial appliances such as these need attention, but because of a lack of frequent monitoring, there can be significant downtime before the required servicing is performed. Often, the company responsible for the appliance is not aware that the machine needs servicing, because the customers simply go elsewhere looking to make their purchase without notifying anyone.

Historically, no practical solution existed to combat this problem. It was too costly to have an employee periodically test each machine for failures. In recent times, however, new low-cost electronics became available that could provide a means to do remote appliance monitoring. Additionally, simple electronics can provide a new alert-based means of reporting a fault condition. For example, if a smart vending machine noticed that it received no sales within the last 24 hours (an unlikely event), it could automatically send an email to notify service personnel of the anomaly.

Ethernet rescue

Enlarge this picture Fig. 1. A smart vending machine reports its status through a Web server, and sends email alerts via the SMTP. A TCP/IP stack and Ethernet hardware complete the connectivity solution.

The de-facto standard for networking computers is Ethernet because it supports data rates from 10 Mbits/s to 10 Gbits/s, and is widely deployed — essentially reaching all office buildings and numerous residential homes. Manufacturers also make sealed connectors and other Ethernet solutions for industrial facilities. Modern advances in silicon technology have also brought Ethernet to the appliance market, where full-blown computers are not needed. For example, the PIC18F67J60 microcontroller from Microchip Technology offers a 10Base-T Ethernet peripheral, in addition to numerous I/O options for appliance monitoring.

Ethernet is here to stay, constantly being upgraded rather than being made obsolete. Given all of the great features of Ethernet, it seems logical to leverage this technology to help reduce machine downtime that results from a lack of automatic remote monitoring.

Building a node

To build an Ethernet node, one needs several different hardware and software modules. At the hardware level, one only needs an Ethernet MAC and PHY, which are both integrated onto the PIC18F97J60 8-bit microcontroller family. However, to send emails and interface with non-proprietary computer terminals, one also needs an embedded TCP/IP software stack. A TCP/IP stack is a collection of standardized protocols that address all of the modern communications needs, such as device addressing, data-error detection and correction, and email transmission, among others.

A minimal smart appliance example is shown in Fig. 1. The depicted vending machine has sensors detecting faults — exhausted soda inventories, or otherwise — that interface to a microcontroller. The microcontroller runs a TCP/IP stack, which automatically obtains a network address via the Dynamic Host Configuration Protocol (DHCP), and then permits a Web server (HTTP) to passively display the status information. Alternatively, email alerts can be sent using the Simple Mail Transport Protocol (SMTP). The on-chip Ethernet MAC and PHY, which permits access to the deployed Ethernet, and the entire TCP/IP stack are all contained inside a single 64-pin, 8-bit microcontroller.

Many silicon vendors provide software TCP/IP stack solutions together with their Ethernet hardware, accelerating the design process. Microchip, for example, has been offering a free TCP/IP stack for its PIC18 microcontrollers for several years, and provides customers with full access to the source code. Without having to worry about the software stack, designers can focus on the user interface and actual functions of their appliances.

Going the distance

Enlarge this picture Fig. 2. Smart vending machines can directly request service from the appropriate personnel, through the use of a cell-phone provider's email-to-SMS bridging.

Ethernet connectivity provides an excellent local ability to monitor appliances from within the same area. However, some applications may find it useful to collect aggregate appliance status reports from a central office. In other cases, it might be useful to notify service personnel immediately of a fault or need for restocking, via a Short Message Service (SMS) message to their cell phone.

To achieve global connectivity, the Internet can be leveraged to provide these services at low cost, and at no cost to the appliance manufacturer. The same TCP/IP protocols used on Ethernet networks are used on the Internet. As a result, a single modem provided by an Internet Service Provider can bridge the gap, with no software changes needed. Fig. 2 shows an example of how a vending appliance could directly contact a service person.

Many cell-phone providers offer the ability to send SMS text messages to a cell phone, merely by sending an email to a particular Internet email address. As a result, adding such notification features to new appliances becomes easy, once the Ethernet/TCP/IP solution is implemented.

Conclusion

Traditional means of determining when an appliance has faulted required waiting for customers to complain. Vending appliances that periodically needed restocking required personnel to poll the devices. The result, in many cases, is lost revenue — either through lost sales or excessive polling. Through the use of modern Ethernet/Internet-working technologies and newer integrated silicon solutions, it becomes possible to decrease appliance downtimes and offer advanced status reporting. Additional value-added features can also be brought to appliances with Ethernet/Internet connectivity, limited only by the developers’ imagination and cost considerations.