The PinPulse shield
The shield gives the Nano a light on 22 of its 28 pins, and brings every pin out three times: the socket the Nano seats in, a male pin strip and a yellow socket strip. The pins without a light are the rails, the reset line and AREF.
What it is
The PinPulse shield is a board 55 x 49 mm with two 4.8 mm mounting holes, 48 mm apart, at its top edge. Down the middle are two 15-way sockets, 8.5 mm tall and 15.24 mm apart, which the Nano seats in. The left one takes the Nano's row B and the right one takes row A, hole for hole.
Outside each socket, on each side, are two more strips: a row of male pins, and a row of yellow 15-way sockets. The names are printed outside them. Everything else is lights.
Which pins have a light
There are 22 lights, red, each in series with a 5.1 kohm resistor, driven by five SN74HC04 chips. TXD and RXD have one, D2 to D12 have one each, A0 to A5 have one each, and so do A6, A7 and D13. A6 and A7 are marked IN, because on the chip they can only be read, never driven. A ~ is printed beside the six pins with PWM.
The pins with no light are VIN, +5V, 3V3, AREF, the two GND rows and the two RST rows. Those are supplies, ground, reset and a reference, not signals a sketch switches.
The light is not on the pin. The pin goes to the input of an inverter, and the light hangs between +5V and the inverter's output; the next page walks through it. What matters here is that the pin sees an input, not a lamp.
Three places for every pin
A signal comes out of the shield in three places that are one wire: the socket under the Nano, the male pin, and the yellow socket. So you can plug a female jumper into a pin or a male jumper into a socket, whichever is on the end of your wire, without ever lifting the Nano.
The back of the shield prints the pin lists for SPI, I2C, UART, PWM and ADC, and the figure shows them on the rows if you pick that view. It also prints what to do about a flickering light: set the pin to output and give it a level. That is the page on the floating pin.
When it does not work
The pin is floating: not driven HIGH or LOW, so the inverter behind its light sees whatever the pin picks up. Set pinMode to OUTPUT and write HIGH or LOW, as the back of the shield says. The page on the floating pin goes through it.
A6 and A7 are analogue-in only on the chip. The shield marks them IN: their lights show the voltage on the pin, and no sketch can switch them.
That is by design. A rail would only ever be lit, and RST and AREF are not pins a sketch drives. The two GND rows and the two RST rows have no light either.
Each shield light takes roughly 0.6 mA by the arithmetic on the next page, assuming a 2 V drop across the red LED. They are meant to be read indoors, not to light a room.
They are the same wire. Use the male pin strip for a female jumper and the yellow socket strip for a male jumper. The row under the Nano is for the Nano.
Why a HIGH pin lights its lamp, and why the pin itself is hardly loaded.
How a pin lights its LED →Edit this page — content/books/nano/the-pinpulse-shield.mdx
Questions about this product
See what other owners have asked, and read their solutions.
This page covers several products. Choose yours to see the right discussions.
Discuss this article
Ask about this page. The answer stays here, on the page it belongs to, for whoever hits the same wall next.