Keith's Electronics Blog

Best Hong Kong never responded again to the claim/dispute process; and when their time ran out last Saturday, PayPal decided in my favor with this message:

We have concluded our investigation into your claim.

We have decided in your favor and have recovered funds from the seller. You have indicated that a partial refund amount of $6.00 USD would be satisfactory.

If the seller’s account has insufficient funds to complete the refund owed to you, please be assured that we will take appropriate action against the seller’s account, which may include limitation of the seller’s account privileges.

And both PayPal and Citibank show that $6 has been transferred from Best Hong Kong back to my credit card, so I guess we’re done here.

Curiously, PayPal’s dispute resolution center has a rather different message when I view the closed case:

We have completed our investigation of this case. We have denied this claim and a refund will not be issued.

Now, I know it’s already been issued, but that kind of message is troubling. So I’ve submitted this to their customer support:

I recently received an email from you saying you had completed your investigation of buyer complaint case #PP-179-609-629, had decided in my favor, and had provided a partial refund as I requested.

However, I just went into your Resolution Center to view the ticket online, and it says you denied the claim and no refund will be issued.

I’m a little concerned by that. Can you explain the discrepancy between the two messages?

As I haven’t heard anything from Best Hong Kong in the week since my last email to them, I assume they’re not planning to get back to me. I just escalated my dispute to a claim, with this notation:

I picked this auction out of various LEDs offered for sale in part because it advertised my choice of free resistors; and I was very careful to follow the seller’s instructions during checkout to specify which resistors I wanted (which I notice they don’t deny).

I would really prefer to have the seller ship me the resistors I specified, completing the auction. However, as I can buy the same resistors (220-ohm 1/4 watt) through Digi-Key (a widely known mail-order catalog) for as low as $5.40 plus shipping, I guess I’d be willing to accept a $6 refund.

Since the error in sending the wrong resistors was made entirely by the seller, and if they’re really not willing to send me the right ones, I don’t see why I should be willing to accept a lesser refund than what it will cost me to replace the resistors from an alternate source. Any other outcome means that the seller’s error costs me money, which doesn’t seem appropriate.

PayPal’s system displayed this confirmation message:

A claim has been filed against this transaction. The seller’s deadline for responding to this claim is . The seller has the option to provide a full refund for the amount of the transaction, offer a full refund if the item is returned in its original condition, offer a partial refund in an amount you agree to, provide proof that a refund was already issued to you, or disagree with your claim. If the seller does not respond by the deadline, the claim will be decided in your favor. You may cancel this case at any time by clicking “Cancel” below.

It occurred to me that I haven’t posted the latest update on data interfacing to the Dallas/Maxim DS1302 real-time clock (RTC) chip; and then I searched and saw that I haven’t posted anything on it. I received the sample chips mid-June and started working with them after I had prototyped the A6276 LED driver and was waiting for my shipment of LEDs. Apparently once I received the LEDs, I was so excited by the bright blue glow that I forgot to get back to the timekeeping functions.

“Auditioning” the 1302

I’m looking at two different timekeeping chips to use in the clock. The DS1340 looks like the better choice but is only available in surface-mount packages, so I’ll need to make a carrier before I can breadboard it to test; thus so far I’ve been testing the DS1302.

The 1302 tracks YY/MM/DD HH:MM:SS plus day of week and choice of 24-hour or AM/PM. It uses an external 32768Hz oscillator and has a V_CC2 input to allow it to run on a lithium backup battery for up to 11 years in the absence of primary power. It doesn’t do daylight savings time, has century-unaware leap year support (but my clock will not still be in use in 2100), and requires you to set day of week manually rather than calculating it algorithmically. It’s not terribly sophisticated–but I don’t need terrible sophistication to get this job done.

It uses a “simple” three-wire interface for data communications:

To write data to the 1302, raise CE, transmit the register address to the 1302 (setting the low bit to indicate a write operation, and clocking each bit), transmit the data (clocking each bit), and lower CE. To read data from the 1302, raise CE and transmit the register address (clearing the low bit, and clocking), continue clocking and read the received data, and lower CE.

But in the Real World . . .

I jumpered it to my Curiously Strong LogoChip and coded up an implementation of the protocol, but was getting totally random data back. The 1302 claims to support clock speeds down to DC (i.e. as slow as you want it to go), so I slowed it down to 1Hz and put the logic probe on it to see whether the bits it was sending matched the bytes I was outputting. After watching it send ultra-high-speed flurries of data back in response to the slow requests I was sending it, I realized it behaves much more predictably when I connect its ground pin to ground instead of leaving it floating. Oopsie.

Once I was actually communicating with the chip with a common voltage reference, I was able to read and display its seconds register. I found that it changed once a second as expected; and I knew its output wouldn’t be a simple count from 0-59, because it uses binary-coded decimal (BCD), where each nybble is the binary coding for the corresponding decimal digit.

I was surprised, though, to see the values alternating high and low: 64, 192, 65, 192, 66, 194, 67, 195. This suggested a bit alignment problem–I wasn’t reading the right bit in the right position. I wrote a Perl script to translate the decimal values into binary with leading zeroes (to make the bits line up so I could scan visually for patterns) and fed it a complete 60-second cycle, with this result:

I needn’t have included the whole thing, because it’s obvious what’s happening. What I thought was the high bit was changing the most rapidly, so it must in fact be the low bit. Somehow the byte got rotated one bit to the right. It’s only fair to mention at this point that the chip will keep repeating its transmitted data as long as you keep clocking it; so a rotation like this simply means that I’m a clock cycle off, not that something utterly bizarre is happening.

I searched my code for an errant clock cycle between the address-write and the data-read, but couldn’t find anything amiss. As an ugly kludge to get it working, I changed the read routine to cycle the clock after reading the bit rather than before, and of course began to get the correct data. Then I reexamined the datasheet and found the slightest justification in their confusing language that this behavior is by design: the first bit from the DS1302 is transmitted on the falling edge of the same clock cycle whose rising edge carried the last bit of the address register. Ewwwww.

I’ve been trying to think of cleverer ways to adapt to the situation, but haven’t come up with any. Clocking after reading works for single-byte reads, and should work (I haven’t tried it yet) for multi-byte reads in burst mode. So I guess I’ll leave it that way.

Here are the first few entries of a correct seconds cycle, in all their glory:

The 1 in the high bit of the high nybble represents that the clock is halted (which it obviously isn’t; not sure what to make of that, unless maybe it’s a write-only register???), the next three bits represent the tens-of-seconds digit, and the lower four bits represent the seconds digit. So this short list here shows seconds 00 – 13.

Higher-Level Timekeeping Functions

In order to be able to interpret the data coming back while testing the read routines, I had already written some functions to parse the time data. I haven’t gone back to test all of them after getting the read working, and I have some cleaning up to do on them anyway. Now that I have a one-digit prototype display working, I think returning to the timekeeping is the next step. Hopefully I can soon integrate the two, so the demo display can show actual seconds information.

Best Hong Kong:

We do preferred to send you $1 to close this dispute. The gift, which is not worth $1 and we did send you the 470ohm resistors already which is perfect for 12VDC power. if you want us to send the extra 220ohm, please close the dispute and we’ll do it.

Me:

I don’t know why you describe the resistors as a gift, because they were part of the auction listing, therefore part of the auction. And while they may be worth less than $1 to you, unfortunately it would cost me $6 to replace them from another source, so I don’t think it’s fair for you to describe their value as less than $1. Also, for what it’s worth, I’m not using 12V power, so the wrong resistors you sent don’t do me any good–that’s why I ordered 220-ohm resistors, which are what I need.

I’m trying to be reasonable and work with you to correct the mistake you made when you sent the wrong resistors, but I’m not willing to close the dispute until I receive the right ones. Again, if you do send the 220-ohm resistors, I will happily close the dispute as soon as I receive them.

Here’s Best Hong Kong’s response to the dispute I opened with PayPal about the resistors not being the value I requested:

We can do 2 options. we refund you $1. or close the dispute and we’ll send you again, 100pcs of 220ohm resistors. by air mail. if you want a trackable shipment, you will need to pay $2.30 for registered air mail charge. if you want the resistors, please close the dispute and then email ken@besthongkong.com your address & a copy of my msg here. we’ll then send the resistor out in our next shipment. Regards, Ken Besthongkong.com

My reply:

I definitely want the replacement 220-ohm resistors–that’s exactly what I’m asking for, so thank you for offering.

But PayPal specifically says I can’t close the dispute until I receive the resistors:

“Likewise, if the seller is going to send a replacement item, don’t close the dispute until you have received it.”

So please go ahead and send them. I understand the overseas shipping will take a little while, and that’s okay; also, I don’t think trackable shipping is necessary. As soon as I receive the resistors, I’ll immediately close the dispute and leave you positive feedback on eBay for correcting the mistake promptly and courteously.

And the entire PayPal “Dispute Resolution and Tips” policy I’m citing:

When should I close this dispute?

Wait until you are 100% satisfied that the dispute is fully resolved before closing the dispute. A closed dispute cannot be re-opened or escalated to a PayPal claim, so before you close your dispute you should ensure that your concerns have been fully addressed. For example, if the seller is going to provide a refund, make sure that the funds are in your account before closing the dispute. Likewise, if the seller is going to send a replacement item, don’t close the dispute until you have received it.

Remember, a dispute will automatically close 20 days after the date it was opened. You should escalate a dispute to a claim if you haven’t fully resolved the issue within 20 days.